What is the main reason for not considering analogous organs as strong evidence of common ancestry?

Correct answer: Their function may be similar but basic structure is different

The governing concept is the distinction between homologous and analogous organs. Analogous organs may perform a similar function because organisms face similar environmental demands, but their basic structure and evolutionary origin are different. Thus wings of insects and birds both help in flight, yet they do not by themselves indicate a common structural origin. Therefore option A is correct; colour, lack of function, and occurrence only in humans are unrelated claims.