Refer to the given dichotomous key and answer the following questions.

Options

A. Which of the following statements is correct regarding the given dichotomous key?
B. The body of organism P is perforated by numerous pores called ostia whereas R possesses special stinging cells called cnidoblasts.
C. The excretory system of Q consists of characteristic flame cells or protonephridia. The body wall of S consists of special stinging cells called choanocytes whereas body of T is differentiated into head, visceral mass and foot.
D. Body of U bears paired locomotory appendages called parapodia.

Answer

A

Explanation

Excretion in Spongia occurs through body surface, i.e., plasma membrane. Bodywall of Obelia (S) is lined by cnidoblast cells and body of molluscs is differentiated into head, visceral mass and foot. Periplaneta bears jointed appendages.