Answer:
The correct answer would be the ischial spine.
Explanation:
The coccygeus muscle or ischiococcygeus muscle is a remnant or residual muscle of the pelvic floor. It is a triangular shape, coupled muscles that present on the top of sacrospinous ligament. It makes the lowest part of the back of the wall of the lesser pelvis.
It acts to support pelvic viscera. Its origin is the top point of the ischial spine, near to the posterior region of the obturator internus.
Thus, the correct answer is the ischial spine.