AIIMS 2018 Biology Phylum Mollusca MCQ Question

Mollusca are characterized by bilateral symmetry and often possess a calcareous shell, which provides protection and support. Option A is incorrect because Mollusca exhibit bilateral symmetry rather than radial symmetry, while option C is false as they are triploblastic, not diploblastic, and possess a radula for feeding. Option D is also incorrect since Mollusca do not exhibit radial symmetry; their body plan is primarily bilateral.