Goitre is caused by deficiency of which hormone–

Correct option is D

Sol. Goitre is the abnormal enlargement of the thyroid gland, most commonly caused by iodine deficiency, which leads to reduced production of thyroid hormones (T3 and T4). The pituitary gland compensates by releasing more TSH (thyroid-stimulating hormone), causing the thyroid to enlarge. It is especially common in hilly areas with iodine-deficient soil and can be prevented by consuming iodized salt.
Explanation of each option:
· (a) Insulin – Incorrect. Insulin regulates blood sugar levels. Its deficiency leads to diabetes, not goitre.
· (b) Estrogen – Incorrect. Estrogen is a female sex hormone involved in menstrual cycle regulation, not related to thyroid gland function.
· (c) Serotonin – Incorrect. Serotonin is a neurotransmitter involved in mood regulation, not hormone responsible for thyroid gland activity.
· (d) Thyroid – Correct. Goitre is directly linked to thyroid hormone deficiency, often due to lack of iodine in the diet.