The maximum biodiversity is found in

The correct answer is C) Tropical rain forests. Species richness peaks where warmth, rainfall and a long growing season all occur together, and tropical rain forests combine all three throughout the year. They cover only about 6 to 7 per cent of the land surface yet hold more than half of the world's known species, which is why they are the classic example of maximum biodiversity.

Why the others fall short:

• A) Tundra: Permafrost, short summers and low temperatures allow very few species, mostly lichens, mosses and hardy shrubs.
• B) Coniferous forests (taiga/boreal): The largest land biome, but it has few tree species and a simple structure, so diversity is low.
• D) Temperate forests: Seasonal climate, frost and dormancy limit species compared with the tropics, though they are richer than taiga.

The core concept is the latitudinal diversity gradient, which links climate stability and productivity to species richness. For Mains, connect this to India's biodiversity hotspots such as the Western Ghats and the Northeast, and to conservation debates under the Convention on Biological Diversity.

Trap: Do not confuse the largest biome (taiga) with the most diverse one, or assume that rich temperate forests beat tropical rain forests in species count.