What can be a main reason for decline in wildlife numbers?

Correct answer: Habitat destruction

The direct answer is A: habitat destruction. Wildlife needs a suitable habitat for food, water, shelter, breeding and protection. When forests, grasslands, wetlands or other habitats are cleared, divided by roads, polluted or converted into farms and buildings, animals lose these necessities. Therefore their numbers may decline, and some species may disappear locally. Option A is correct because habitat destruction directly removes the places where animals live. Option B, habitat protection, normally helps wildlife survive and therefore is not a main cause of decline. Option C, saving water sources, generally supports wildlife by preserving drinking water and aquatic life; it is a protective action, not a cause of decline. Option D, making wildlife corridors, connects separated habitats and helps animals move safely, so it also supports conservation. The word “main reason” points to a harmful human activity, and habitat loss is one of the most important threats to biodiversity. Memory cue: no habitat means no food, shelter or breeding place.