Aggregate fruit develops from
A. Syncarpous ovary
B. Multicarpellary, syncarpous ovary
C. Unilocular ovary
D. Multicarpellary, apocarpous ovary

Hint: An important characteristic of angiosperms is the formation of fruit. Gynoecium containing more than one carpel and which are free from each other can form a single fruit and the fruit is the fertilized ovary.

Complete answer: The female reproductive part of the flower is gynoecium. The gynoecium is composed of pistils. If the gynoecium consists of a single pistil then it is monocarpellary condition and if more than one pistil then it is multicarpellary condition. In a multicarpellary condition, if pistils are fused together then it is called syncarpous and if the pistils are free then it is called apocarpous. Syncarpous condition is found in Papaver and the apocarpous condition is found in Michelia. The final product of sexual reproduction is the seed. At the end of sexual reproduction ovary develops into fruit and ovules develop into seeds. The fruits are classified into three categories that are simple fruits, aggregate fruits, and composite fruits. Aggregate fruit is a collection of simple fruitlets that develops from multicarpellary apocarpous ovaries. aggregate fruit is also called etaerio. Examples: etaerio of achenes (strawberry), etaerio berries (custard apple), etaerio of follicles (calotropis).
Hence, the correct answer is Option D.

Note: Not all fruits are the products of sexual reproduction, for example, parthenocarpic fruits are the ones that develop without fertilization. Similarly, not all ovaries develop into fruits, for example, in apples and cashew the fruits develop from the thalamus. Such fruits are false fruits.