A Muscle That Constricts an Opening is A/an

Question

A muscle that constricts an opening is a/an
A)extensor.
B)levator.
C)antagonist.
D)sphincter.

Accepted Answer

A sphincter is a type of muscle that functions to constrict or close an opening, such as the esophageal sphincter or anal sphincter. Therefore, the best choice for this question is D, sphincter.