Key concepts of Darwinian theory of evolution are:

The correct answer is Option (1) → Branching descent and natural selection

Darwin’s theory rests on two ideas. Branching descent means that all organisms come from common ancestors, and the lines of descent branch like a tree. Natural selection means that organisms best fitted to the environment leave more offspring.

(1) Branching descent and natural selection — Correct. These are the two key concepts of the Darwinian theory.

(2) Unbranching descent and natural selection — Incorrect. Descent in Darwin’s theory branches. A single unbranching line would not explain the variety of species.

(3) Convergent evolution and natural selection — Incorrect. Convergent evolution means that unrelated organisms in similar surroundings develop similar features. It is not one of the two key concepts.

(4) Divergent evolution and natural selection — Incorrect. Divergent evolution is the result of branching descent, where related groups come to differ. NCERT names branching descent itself as the key concept.

Note: A similar question was also asked in CUET (UG) 2026 on 20-05-2026 (Slot 2).

NCERT Extract:
Biological Evolution – “… Branching descent and natural selection are the two key concepts of Darwinian Theory of Evolution (Figures 6.7 and 6.8).”