Small amounts of iodine are necessary in our diet to

prevent pellagra
stimulate pituitary gland
stimulate clotting of blood
compensate for underactive the thyroid gland

The correct answer is: D. compensate for underactive the thyroid gland.

Iodine is a mineral that is essential for the production of thyroid hormones. Thyroid hormones are responsible for regulating metabolism, growth, and development. Iodine deficiency can lead to a condition called hypothyroidism, which can cause a variety of symptoms, including fatigue, weight gain, hair loss, and dry skin.

Pellagra is a disease caused by a deficiency of niacin (vitamin B3). Niacin is essential for the production of enzymes that are involved in energy metabolism. Pellagra can cause a variety of symptoms, including diarrhea, dermatitis, and dementia.

The pituitary gland is a small gland located at the base of the brain. It produces a number of hormones that are essential for growth, development, and reproduction. The pituitary gland is not affected by iodine deficiency.

Clotting of blood is a complex process that involves a number of different factors. Iodine is not a necessary factor in blood clotting.

Therefore, the correct answer is: D. compensate for underactive the thyroid gland.