Biology

Elephant trunk and human hand are not homologous structures because they do not share a common evolutionary origin. The elephant trunk evolved from the nose and upper lip, while the human hand evolved from the forelimb of early vertebrates. Although both serve similar functions (grasping, handling), they evolved differently from distinct anatomical structures, making them not homologous.

For A: These are homologous structures. Despite their different functions (grasping in humans, flying in bats), both evolved from the forelimbs of a common vertebrate ancestor, making them homologous.