Molluscs That Exhibit Torsion Have the Unusual Situation of Dealing

Multiple Choice

Molluscs that exhibit torsion have the unusual situation of dealing with their anus discharging directly over their head and mouth. Which of the following arguments can explain this phenomenon?

A) It is a larval adaptation, allowing protective withdrawal of the head into the mantle cavity.
B) It increases the ventilatory current over the gills during forward locomotion.
C) It allows the anterior and posterior openings of the digestive tract to be adjacent and the body protected within the shell.
D) It allows the ability to completely close the shell entrance and seal it with an operculum.
E) All of the arguments could be equally valid.