Question

which hormone stimulates osteoclast proliferation and bone resorption? a.) parathyroid hormone (pth) b.) sex hormones c.) calcitriol d.) thyroxine

Explanation:

Parathyroid hormone (PTH) is known to stimulate osteoclast proliferation and bone resorption. Osteoclasts break down bone tissue. PTH acts on osteoblasts (bone - forming cells) to secrete factors that activate osteoclasts. Sex hormones (like estrogen and testosterone) mainly play a role in bone maintenance and growth during puberty and also have an inhibitory effect on bone resorption to some extent. Calcitriol (the active form of vitamin D) promotes intestinal calcium absorption. Thyroxine (a thyroid hormone) is more involved in regulating metabolism rather than directly stimulating osteoclast - related bone resorption.

Answer:

A. Parathyroid hormone (PTH)