If two organisms possess similar structures that serve similar functions but don't possess a common ancestor that shared that structure, then the structures are classified as a. homologous. b. morphologies. c. vestigial. d. analogous.

D. analogous.

Explanation:

Analogous organs can be defined as organs, which show similar functions, but do not having common origins. Organisms that possess analogous organs do not share common ancestor as their organs are derived from different origins.

Examples of analogous organs include wings of bats, birds, and birds which are evolved independently, but share common function (flying).

Thus, the correct answer is option (D).