The correct option is D Hairs of the ovary wall
In a fruit, the endocarp is the inner layer surrounding the seed. In Hesperidium type of fruit, the epicarp forms the cover, the mesocarp is fibrous and the endocarp bends inwards giving rise to a chamber from which hair-like structures are formed. These are juicy and form the edible part in orange and lemon. Thus, the correct answer is option C.