Feminization of the female genitalia is caused by the production of estrogens by the gonads during early fetal development.

Correct Answer: B

Rationale: False (B): Feminization occurs due to no androgens, not estrogen (which acts later). True (A) is incorrect.

Correct Answer: B

Rationale: False (B): Secretory phase builds endometrium; menstrual phase discharges it. True (A) is incorrect.

Correct Answer: B

Rationale: False: Epiglottis elevates (not depresses) to cover glottis (B). Slack cords lower pitch (A), whispering avoids vibration (C), testosterone enlarges larynx (D).

Correct Answer: B

Rationale: Elevated CO₂ causes respiratory acidosis (B) from H⁺ increase. Breathing increases (not decreases, A, D), pressure receptors (C) are unrelated.

Correct Answer: A

Rationale: Surfactant (A) lowers alveolar surface tension, aiding expansion. It doesn’t affect P_CO₂ (B), isn’t mucus (C), or reduce pleural friction (D).