Which one of the following statement is not applicable to leeches?

The correct option is D Clitellum is a permanent structure
Leech belongs to class Hirudinea.

Parapodia or setae is absent in leeches. Therefore, this statement is correct.

Clitellum is a temporary structure and not permanent structure. Therefore, this statement is incorrect.

Fertilization is internal as it is inside the vagina. Therefore, this statement is correct.

The packing material in body of leech is botryoidal tissue. It is composed of two different cells, granular botryoidal cells and flattened endothelial-like cells localized in the loose connective tissue between the gut and the body wall sac. Therefore this statement is correct.

Therefore, the correct answer is option B.