Which two hormones are involved in calcium homeostasis? a. glucagon and calcitonin b. parathyroid hormone and thyroid hormone c. calcitonin and parathyroid hormone d. thyroid hormone and glucagon

The correct option is C.
The parathyroid hormone and calcitonin hormone are the ones responsible for regulating the level of calcium in the blood.  Calcitonin which is secreted by the thyroid gland inhibits osteoclasts and stimulates osteoblasts thus decreasing blood calcium level.
The parathyroid hormone which is secreted by parathyroid glands inhibits osteoblasts and stimulates osteoclasts. It also reduces the output of calcium by the kidney and promotes the absorption of calcium at the small intestines, thus increasing the blood calcium level.

The return of the wolf to yellowstone national park will probably affect the bird population to some degree, not significantly. while wolves will hunt birds when necessary, they prefer to hunt larger prey. the bird population will most likely only be affected when hunting is scarce for the wolves. birds of prey will also probably not be affected as much as other birds who spend more time on the ground hunting for food as the tend to spend more time in the air or in trees since they do not need to stay on the ground for long due to the nature of the way they hunt.

The answer to your question is vagina