**Core Concept**
Sheehan's syndrome is a rare but serious complication of postpartum hemorrhage, characterized by the necrosis of the pituitary gland. This condition leads to a deficiency in one or more of the pituitary hormones, resulting in various endocrine abnormalities.

**Why the Correct Answer is Right**
Sheehan's syndrome typically presents with symptoms of hypopituitarism, including amenorrhea, infertility, and decreased libido. The condition is caused by the necrosis of the pituitary gland, which can occur due to severe blood loss during delivery. The resulting deficiency in anterior pituitary hormones, such as growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin, can lead to various systemic complications.

**Why Each Wrong Option is Incorrect**
**Option A:** Amenorrhea - This is a common symptom of Sheehan's syndrome due to the deficiency of gonadotropin-releasing hormone (GnRH), which leads to decreased FSH and LH levels, resulting in amenorrhea.
**Option B:** Galactorrhea - This is not typically seen in Sheehan's syndrome, as the condition is characterized by a deficiency of prolactin, which is the hormone responsible for milk production.
**Option C:** Weight loss - This can occur in Sheehan's syndrome due to the deficiency of growth hormone (GH), which plays a crucial role in regulating body weight and metabolism.
**Option D:** Hypothyroidism - This can occur in Sheehan's syndrome due to the deficiency of thyroid-stimulating hormone (TSH), which leads to decreased thyroid hormone production.

**Clinical Pearl / High-Yield Fact**
Sheehan's syndrome should be suspected in any postpartum woman who presents with amenorrhea, infertility, or decreased libido, particularly if she has a history of severe postpartum hemorrhage.

**Correct Answer: B. Galactorrhea**