Endocrinology

Progesterone (A): Primarily produced by the corpus luteum (IV) during the menstrual cycle and by the placenta during pregnancy.
Relaxin (B): Produced by the ovary (II) and also by the placenta during pregnancy. It helps relax ligaments in preparation for childbirth.
Melanocyte-stimulating hormone (C): Produced by the pars intermedia (I) of the pituitary gland.
Catecholamines (D): Epinephrine and norepinephrine are produced by the adrenal medulla (III).

Anti-diuretic hormone (ADH), also known as vasopressin, is synthesized in the hypothalamus and stored in the posterior pituitary gland. FSH, LH, and ACTH are synthesized and released by the anterior pituitary.

The adrenal medulla releases epinephrine and norepinephrine (adrenaline and noradrenaline). These hormones prepare the body for "fight or flight" responses. They increase heart rate and contraction strength (D), stimulate glucose release from the liver (hyperglycemic effect - B), and cause piloerection (hair standing on end - C). They cause pupillary dilation, not constriction (A).

Insulin is a protein hormone. If taken orally, it would be broken down by digestive enzymes in the stomach and small intestine, rendering it ineffective. This is why insulin is typically administered by injection, allowing it to enter the bloodstream directly.