Which one of the following pairs of vegetables is an example of homologous structures?
(A) Potato and sweet potato
(B) Carrot and radish
(C) Carrot and tomato
(D) Tomato and radish
Homologous structures are similar in origin, but they perform different functions. Carrot and radish are underground roots, so they represent homologous structures.
Hence, the correct option is B.