Homology is related to:

The correct answer is Option (2) → Divergent evolution

(1) Convergent evolution — Incorrect. Convergent evolution gives analogous organs. These are different structures that do the same job, like the wings of a butterfly and of a bird.

(2) Divergent evolution — Correct. Homologous organs have the same basic structure but do different jobs. The forelimbs of whales, bats, cheetahs and humans all have the same bones. The same structure changed in different directions to suit different needs. This is divergent evolution, and homology shows common ancestry.

(3) Founder effect — Incorrect. This is a change in gene frequency when a small group settles in a new place and starts a new population. It is about gene frequencies, not about the structure of organs.

(4) Saltation — Incorrect. Saltation means a single large jump in variation, caused by a large mutation. It has nothing to do with homology.

NCERT Extract:
What Are the Evidences for Evolution? – “… Though these forelimbs perform different functions in these animals, they have similar anatomical structure – all of them have humerus, radius, ulna, carpals, metacarpals and phalanges in their forelimbs. Hence, in these animals, the same structure developed along different directions due to adaptations to different needs. This is divergent evolution and these structures are homologous. Homology indicates common ancestry.”