The correct option is D A cluster of compactly born flowers on an axis
Pineapple fruit develops from a cluster of compactly borne flowers on an axis. Pineapple is a multiple fruit. Multiple fruits, also called as collective fruits, are fruits that are formed from a cluster of flowers called as an inflorescence. Each flower in the inflorescence produces a fruit, but these mature into a single mass. An multiple fruit is a fruit that develops from the merger of several ovaries that were separate in a single flower. In contrast, a simple fruit develops from one ovary. Not all flowers with multiple ovaries form aggregate fruit, the ovaries of some flowers do not become tightly joined together to make a larger fruit.
Therefore, the correct answer is option D.