Question

Which of the following is not possible?

a. radially symmetrical diploblast

b. diploblastic eucoelomate
c. protostomic coelomate

d. bilaterally symmetrical deuterostome

Short answer

Option b is correct.

Step-by-step solution

Introduction

Further subdivision of animals with three germ layers (triploblasts) results in the separation of animals that may develop an internal body cavity derived from mesoderm, called a coelom, and those that do not.

Explanation of correct option

b. diploblastic eucoelomate : Eucoelomates are animals with a true coelom. The presence/absence of a coelom is a division of triploblasts only. Thus, a diploblast cannot be a eucoelomate.

Explanation of incorrect options

a. radially symmetrical diploblast : All diploblasts are radially, biraldially or rotationally symmetrical.

c. protostomic coelomate : Protostomic coelomates include mollusks, annelids, arthropods, pogonophorans

d. bilaterally symmetrical deuterostome: Bilaterally symmetrical deuterostome include members of the phylum chordata.