Reliability of the study is determined through

Correct Answer: B

Rationale: Reliability, consistency of measurement, is tested via a pilot study. 'Pilot study,' is correct because it assesses tool reliability (e.g., test-retest), per research methods (e.g., Cronbach). 'Carefully designed questionnaire,' aids reliability but doesn't test it. 'Hypothesis testing,' evaluates validity, not consistency. 'Data analysis,' interprets results, not reliability. Pilot studies' role in pre-testing reliability distinguishes B as the accurate answer.

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: Oxytocin, from the posterior pituitary, triggers milk ejection by contracting myoepithelial cells in the breast. 'Oxytocin,' is correct, per physiology texts like Costanzo, distinct from milk production. 'Progesterone,' supports pregnancy, not ejection. 'Prolactin,' stimulates milk synthesis. 'Oestrogen,' aids breast development. Oxytocin's specific let-down reflex role makes C the accurate answer, critical in lactation.

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.