The correct option is D Sweet potato and potato are homologous structures
Thorns and tendrils of Bougainvillea and Cucurbita respectively are homologous structures. Whales, bats, cheetahs, and humans share similarities in the forelimbs bone pattern, hence they are homologous structures. The comparative anatomy and morphology helps in studying evolution as it shows similarities and differences among organisms of today with those that existed years ago.
Sweet potato is a modified root and potato is a modified stem. These are analogous structures.