Correct Answer: C

Rationale: Rationale for choice C (FSH) being correct: 1. FSH stimulates Sertoli cells in the testes. 2. Sertoli cells produce androgen binding globulin (ABG). 3. ABG binds to testosterone, regulating its availability. 4. FSH indirectly influences testosterone levels via ABG production. Summary of incorrect choices: A. LH stimulates Leydig cells to produce testosterone, not Sertoli cells. B. GnRH regulates the release of FSH and LH but does not directly stimulate ABG production. D. Oxytocin is not involved in the regulation of Sertoli cells or ABG production in males.

Correct Answer: A

Rationale: Step-by-step rationale for why answer A is correct: 1. Oxytocin is synthesized in the hypothalamus and released into the bloodstream. 2. In the plasma, oxytocin binds to neurophysin, a carrier protein. 3. This binding helps stabilize oxytocin and regulate its release and distribution. 4. Therefore, choice A is correct as oxytocin is bound to neurophysin in plasma. Summary: - Choice B is incorrect as oxytocin stimulates milk ejection, not inhibits milk production. - Choice C is incorrect as oxytocin promotes myometrial contraction during labor. - Choice D is incorrect as oxytocin can enhance sperm motility, not inhibit it.

Correct Answer: C

Rationale: The correct answer is C: Purple skin striae. This is the most common sign of Cushing's syndrome due to the excessive production of cortisol leading to thinning of the skin and formation of purple stretch marks. Hirsutism (A) is excessive hair growth, not specific to Cushing's. Obesity (B) can be a symptom, but it is not the most common. Skin hyperpigmentation (D) is seen in Addison's disease, not Cushing's.

Correct Answer: C

Rationale: The correct answer is C: Bi-temporal hemianopia. Pituitary adenoma compressing the optic chiasm typically leads to bi-temporal hemianopia due to compression of the crossing fibers from the nasal visual fields. This results in loss of peripheral vision in both temporal visual fields. A: Bilateral inferior visual field deficits and B: Bilateral superior visual field deficits are less likely as they are not typical patterns associated with optic chiasm compression. D: Right homonymous hemianopia is incorrect as it is not associated with compression of the optic chiasm by a pituitary adenoma.

Correct Answer: B

Rationale: The correct answer is B: Chronic pancreatitis. Hypoglycemia is not typically associated with chronic pancreatitis as it is more related to pancreatic insufficiency and impaired glucose regulation. A: Glycogen storage disease can lead to hypoglycemia due to the inability to properly release stored glucose. C: Galactosaemia can cause hypoglycemia due to the impaired breakdown of galactose into glucose. D: Post-gastrectomy can lead to hypoglycemia due to rapid glucose absorption and altered hormonal responses.