Question

which bone cells increase blood calcium levels when active?
osteoblasts
osteoclasts
osteoprogenitor cells
osteocytes

Explanation:

Osteoclasts break down bone tissue, releasing calcium into the bloodstream, thus increasing blood - calcium levels. Osteoblasts build bone, osteoprogenitor cells differentiate into osteoblasts, and osteocytes are mature bone cells that maintain bone tissue but do not directly increase blood - calcium levels.

Answer:

B. Osteoclasts