Answer:
A.
Explanation:
I've had to answer this before
Answer: Option A) Parathyroid glands
Explanation:
The Parathyroid gland located in the neck region helps in the secretion of an hormone called Parathormone.
This hormone helps to raise the levels of calcium ions in the body, by preventing the loss of calcium ions through urine, and also preventing excess deposit of calcium ions in the bone, thus regulating bone density.
The small intestines have microvilli in the lining which help to increase the surface area of the small intestines and help to absorb nutrients.