Skin biopsy is not usually necessary for confirming the diagnosis of serum sickness because

Correct Answer: D

Rationale: Histopathological findings in serum sickness are nonspecific, so diagnosis is typically based on clinical presentation and complement studies.

Correct Answer: B

Rationale: Impaired communication and social interaction are core features of ASDs, distinguishing them from other developmental disorders.

Correct Answer: D

Rationale: Ceftazidime does not share an identical side chain with penicillins, making it a safer option in penicillin-allergic patients.

Correct Answer: C

Rationale: Bacterial sepsis is a common cause of sudden hypotension in VLBW infants due to systemic infection and inflammatory response. The other conditions can cause hypotension but are less likely to present suddenly.

Correct Answer: C

Rationale: Jaundice with a bilirubin level >12 mg/dL in a full-term infant is common and may not require investigation unless other risk factors are present. The other conditions warrant further investigation.