A 10-year-old boy has a history of hyperactivity, declining school performance and daytime sleepiness. Which of the following investigations will lead to the MOST likely diagnosis?

Correct Answer: D

Rationale: Sleep-disordered breathing (e.g., sleep apnea) can cause daytime sleepiness, hyperactivity, and poor performance. An overnight polysomnogram diagnoses this. CT (A) and EEG (B) assess structural/seizure issues. Testing (C) evaluates learning, not sleep.

Correct Answer: D

Rationale: The Moro reflex (startle reflex) occurs when a sudden stimulus causes the arms to extend outward then flex inward, common in newborns. Tonic neck (A) involves head-turning asymmetry. Rooting (B) aids feeding. Gag (C) prevents choking.

Correct Answer: B

Rationale: Community-acquired infections occur outside healthcare settings, not after admission (which is hospital-acquired). Option B (False) is correct.

Correct Answer: E

Rationale: Substance use explains irritability, irresponsibility, and declining grades with a friend group change, common in adolescence. Bipolar (A) and depression (C) may affect mood but lack social shift specificity. Conduct (B) involves aggression, not necessarily grades.

Correct Answer: A

Rationale: The hepatitis B vaccine is administered as a 3-dose series (typically at 0, 1, and 6 months) for full immunization in infants, children, and adults. Choice B (MMR) is a 2-dose series (at 11-12 months and 4-6 years). Choice C (Hepatitis A) is a 2-dose series (6 months apart). Choice D (HPV) can be a 2- or 3-dose series depending on age at initiation (2 doses if started before age 15, 3 doses if started at 15 or older), but hepatitis B is the most consistently recognized 3-dose series among these options.