The control of calcitonin excretion is an example of direct

regulation

Endocrine regulation

Explanation:

Calcitonin is a hormone secreted by C-cells of the thyroid gland. It regulation calcium, phosphate and potassium levels in the blood fluid. It controls calcium level in the blood. It reduces the activity of osteoclasts the cells which breaks the activity of bones, the calcium in bone is released into the blood stream when bone is broken down.