The correct option is
C Both (a) and (b)
Hypothyroidism (underactive thyroid) is a condition in which your thyroid gland doesn't produce enough of certain crucial hormones.
- Myxedema is a term generally used to denote severe hypothyroidism.
- Cretinism is a condition characterized by physical deformity and learning difficulties that are caused by congenital thyroid deficiency (hypothyroidism).
- Exophthalmic goiter is an endocrine disorder that is the most common cause of hyperthyroidism.
So, the correct option is C.