Which of the following is the most widely accepted method for limiting human population size?

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Regional variation and impacts. Human population projections under the BAU levels of population growth (2013 matrix; Scenario 1) for 14 subregions (R1–R14; see below for country composition). Regional shading indicates relative mean population density projected for 2100: white shading = 0 persons km−2 to darker shading = 656.6 persons km−2). Values next to each region line (legends) indicate the ratio of the projected 2100 population (N2100) to the 2013 start population (N2013). Red hatched overlay indicates position of global Biodiversity Hotspots (a–ii: see below for full Hotspot list). Full Hotspot listing per region and associated projected values are also provided in Table S2. Subregion country composition (boldface indicates region number on the map): Africa D, Region 1: Angola (AGO), Benin (BEN), Burkina Faso (BFA), Cameroon (CMR), Cape Verde (CPV), Algeria (DZA), Gabon (GAB), Ghana (GHA), Guinea (GIN), Gambia (GMB), Guinea-Bissau (GNB), Equatorial Guinea (GNQ), Liberia (LBR), Madagascar (MDG), Mali (MLI), Mauritania (MRT), Mauritius (MUS), Niger (NER), Nigeria (NGA), Senegal (SEN), Sierra Leone (SLE), Sao Tome and Principe (STP), Seychelles (SYC), Chad (TCD), Togo (TGO); Africa E, Region 2: Burundi (BDI), Botswana (BWA), Central African Republic (CAF), Côte d’Ivoire (CIV), The Democratic Republic of the Congo (COD), Congo (COG), Eritrea (ERI), Ethiopia (ETH), Kenya (KEN), Lesotho (LSO), Mozambique (MOZ), Malawi (MWI), Namibia (NAM), Rwanda (RWA), Swaziland (SWZ), United Republic of Tanzania (TZA), Uganda (UGA), South Africa (ZAF), Zambia (ZMB), Zimbabwe (ZWE); Americas A, Region 3: Canada (CAN), Cuba (CUB), United States (USA); Americas B, Region 4: Argentina (ARG), Antigua and Barbuda (ATG), Bahamas (BHS), Belize (BLZ), Brazil (BRA), Barbados (BRB), Chile (CHL), Colombia (COL), Costa Rica (CRI), Dominica (DMA), Dominican Republic (DOM), Grenada (GRD), Guyana (GUY), Honduras (HND), Jamaica (JAM), Saint Kitts and Nevis (KNA), Saint Lucia (LCA), Mexico (MEX), Panama (PAN), Paraguay (PRY), El Salvador (SLV), Suriname (SUR), Trinidad and Tobago (TTO), Uruguay (URY), Saint Vincent and the Grenadines (VCT), Venezuela (VEN); Americas D, Region 5: Bolivia (BOL), Ecuador (ECU), Guatemala (GTM), Haiti (HTI), Nicaragua (NIC), Peru (PER); Eastern Mediterranean B, Region 6: United Arab Emirates (ARE), Bahrain (BHR), Cyprus (CYP), Islamic Republic of Iran (IRN), Jordan (JOR), Kuwait (KWT), Lebanon (LBN), Libyan Arab Jamahiriya (LBY), Oman (OMN), Qatar (QAT), Saudi Arabia (SAU), Syrian Arab Republic (SYR), Tunisia (TUN); Eastern Mediterranean D, Region 7: Afghanistan (AFG), Djibouti (DJI), Egypt (EGY), Iraq (IRQ), Morocco (MAR), Pakistan (PAK), Somalia (SOM), Sudan (SDN), Yemen (YEM); Europe A, Region 8: Andorra (AND), Austria (AUT), Belgium (BEL), Switzerland (CHE), Czech Republic (CZE), Germany (DEU), Denmark (DNK), Spain (ESP), Finland (FIN), France (FRA), United Kingdom (GBR), Greece (GRC), Croatia (HRV), Ireland (IRL), Iceland (ISL), Israel (ISR), Italy (ITA), Luxembourg (LUX), Monaco (MCO), Malta (MLT), The Netherlands (NLD), Norway (NOR), Portugal (PRT), San Marino (SMR), Slovenia (SVN), Sweden (SWE); Europe B, Region 9: Albania (ALB), Armenia (ARM), Azerbaijan (AZE), Bulgaria (BGR), Bosnia and Herzegovina (BIH), Georgia (GEO), Kyrgyzstan (KGZ), The Former Yugoslav Republic of Macedonia (MKD), Montenegro (MNE), Poland (POL), Romania (ROU), Serbia (SRB), Slovakia (SVK), Tajikistan (TJK), Turkmenistan (TKM), Turkey (TUR), Uzbekistan (UZB); Europe C, Region 10: Belarus (BLR), Estonia (EST), Hungary (HUN), Kazakhstan (KAZ), Lithuania (LTU), Latvia (LVA), Moldova (MDA), Russian Federation (RUS), Ukraine (UKR); Southeast Asia B, Region 11: Indonesia (IDN), Sri Lanka (LKA), Thailand (THA), East Timor (TLS); Southeast Asia D, Region 12: Bangladesh (BGD), Bhutan (BTN), India (IND), Maldives (MDV), Myanmar (MMR), Nepal (NPL), Democratic People’s Republic of Korea (PRK); Western Pacific A, Region 13: Australia (AUS), Brunei Darussalam (BRN), Japan (JPN), New Zealand (NZL), Singapore (SGP); Western Pacific B, Region 14: China (CHN), Cook Islands (COK), Fiji (FJI), Federated States of Micronesia (FSM), Cambodia (KHM), Kiribati (KIR), Republic of Korea (KOR), Lao People’s Democratic Republic (LAO), Marshall Islands (MHL), Mongolia (MNG), Malaysia (MYS), Niue (NIU), Nauru (NRU), Philippines (PHL), Palau (PLW), Papua New Guinea (PNG), Solomon Islands (SLB), Tonga (TON), Tuvalu (TUV), Vietnam (VNM), Vanuatu (VUT), Samoa (WSM). Biodiversity Hotspots: a, Tropical Andes; b, Mesoamerica; c, Caribbean Islands; d, Atlantic Forest; e, Tumbes-Chocó-Magdalena; f, Cerrado; g, Chilean Winter Rainfall-Valdivian Forests; h, California Floristic Province; I, Madagascar and the Indian Ocean Islands; j, Coastal Forests of Eastern Africa; k, Guinean Forests of West Africa; l, Cape Floristic Region; m, Succulent Karoo; n, Mediterranean Basin; o, Caucasus; p, Sundaland; q, Wallacea; r, Philippines; s, Indo-Burma, India and Myanmar; t, Mountains of Southwest China; u, Western Ghats and Sri Lanka; v, Southwest Australia; w, New Caledonia; x, New Zealand; y, Polynesia-Micronesia; z, Madrean Pine-Oak Woodlands; aa, Maputaland-Pondoland-Albany; bb, Eastern Afromontane; cc, Horn of Africa; dd, Irano-Anatolian; ee, Mountains of Central Asia; ff, Eastern Himalaya, Nepal; gg, Japan; hh, East Melanesian Islands; ii, Forests of East Australia.