Final answer:
Colpectasia is the dilatation of the vagina. The walls of the vagina are lined with an inner mucous membrane with transverse folds called rugae, allowing for flexibility and expansion.
Step-by-step explanation:
Colpectasia is the dilatation of the vagina, option a) in the given question. The vagina is a muscular canal that serves as the entrance to the reproductive tract. It can expand to accommodate intercourse and childbirth. The walls of the vagina are lined with an inner mucous membrane with transverse folds called rugae, allowing for flexibility and expansion.