Correct Option (A):
Global warming, fragmentation of habitat, and invasion of alien species are significant threats to biodiversity.
- Global warming leads to changes in climatic patterns, sea-level rise, and extreme weather events, altering habitats and forcing species to adapt or migrate, often beyond their capacity. This can lead to species extinction.
- Fragmentation of habitat occurs when large, continuous habitats are divided into smaller, isolated patches, typically due to human activities like deforestation or urbanization. This reduces habitat area, isolates populations, restricts gene flow, and increases vulnerability to local extinction.
- Invasion of alien species (also known as exotic or invasive species) refers to the introduction of non-native species into an ecosystem. These species can outcompete native species for resources, prey upon them, introduce diseases, or alter the ecosystem, leading to a decline in native biodiversity.
Incorrect Options:
- Promotion of vegetarianism is a dietary choice and does not directly pose a threat to biodiversity. In some contexts, it might even reduce the ecological footprint associated with meat production, potentially benefiting biodiversity indirectly. Therefore, statement 4 is not a threat.
- Option (B) "2 and 3 only" is incorrect because it excludes global warming, which is a major threat.
- Option (C) "1 and 4 only" is incorrect because statement 4 is not a threat to biodiversity.
- Option (D) "1, 2, 3 and 4" is incorrect because it includes statement 4, which is not a threat.