Approximately 80% of all asthmatic patients report disease onset prior to the age of

Correct Answer: C

Rationale: Most cases of asthma develop before age 6, highlighting early-life exposures and genetic predisposition as key factors in disease onset.

Correct Answer: D

Rationale: Vitamin A deficiency is not associated with a large anterior fontanel. The other conditions listed can cause delayed fontanel closure or enlargement.

Correct Answer: B

Rationale: Prostaglandin E1 maintains the patency of the ductus arteriosus, allowing blood to bypass obstructed or underdeveloped pulmonary circulation, improving oxygenation in cyanotic congenital heart diseases like pulmonary atresia or transposition of the great arteries.

Correct Answer: B

Rationale: In pneumothorax, air accumulation causes lung collapse, shifting the mediastinum to the opposite side. Decreased breath sounds, hyperresonance on percussion, and absent fremitus are typical findings.

Correct Answer: B

Rationale: The correct answer is B. The best age to introduce solid foods into an infant's diet is typically between 4 to 6 months. At this age, the infant's digestive system has matured enough to handle more complex nutrients, and they have likely lost the extrusion reflex, making swallowing easier. It is an important transition period for introducing new foods.