Final answer:
Early gastropods had a bilaterally symmetrical, non-twisted shell known as a planospiral or coiled shell, distinct from later torsion processes.
Step-by-step explanation:
Early gastropods had a bilaterally symmetrical shell that did not twist to the right or left. This type of shell is referred to as a planospiral shell, which is like a garden hose wound up. While gastropods later developed torsion, causing their viscera to twist and their shells to potentially coil in either direction, the initial symmetry displayed in the early shells was planospiral and not a result of torsion. Gastropods are a diverse class of animals with a variety of shell shapes, and some species even lack shells entirely. However, what's notable is that torsion refers to the twisting of the visceral mass and is separate from the coiling of the shell. The correct answer to the student's question is c. Coiled Shell.