The mineral found in the thyroid gland and affects the rate of metabolism is

Correct Answer: B

Rationale: Iodine is essential for thyroid hormone synthesis (T3 and T4), regulating metabolism. 'Iodine,' is correct, per endocrinology texts like Williams' Textbook of Endocrinology, where iodine deficiency disrupts metabolic rate. 'Iron,' is in hemoglobin, not thyroid-specific. 'Calcium,' affects bones and signaling, not metabolism via thyroid. 'Magnesium,' supports enzymatic function, not thyroid-related metabolism. Iodine's incorporation into thyroxine, directly influencing basal metabolic rate, makes B the precise answer, critical to thyroid physiology.

Correct Answer: C

Rationale: Vitamin C (ascorbic acid) prevents scurvy by aiding collagen synthesis, essential for connective tissue. 'Vitamin C,' is correct, per nutrition texts like Shils, reversing symptoms like bleeding gums. 'Vitamin A,' supports vision. 'Vitamin B,' is a group, none specific to scurvy. 'Vitamin D,' aids bone health. Vitamin C's historical link to scurvy prevention, notably in sailors, makes C the accurate answer.

Correct Answer: C

Rationale: The small intestine averages 7 meters in adults, varying (6-7 m). '7 m,' is correct, per anatomy (e.g., Tortora), spanning duodenum, jejunum, and ileum. '3 m,' is too short. '5 m,' underestimates. '9 m,' exceeds typical length. The 7 m standard reflects its absorptive expanse, making C the accurate answer.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.