Which hormonal deficiency is responsible for the following:
$(a)$ Diabetes mellitus
$(b)$ Goiter
$(c)$ Cretinism.

(N/A) Diabetes mellitus is characterized by abnormally high glucose levels in the blood due to the deficiency of the hormone insulin.
$(b)$ Goiter is characterized by an abnormal enlargement of the thyroid gland due to the deficiency of thyroxine hormone in the body.
$(c)$ Cretinism is characterized by stunted growth and mental retardation in children due to the deficiency of thyroid hormones during fetal development or early infancy.