A 5-day-old infant presents with severe heart failure, poor perfusion, and a gallop rhythm. What is the most likely diagnosis?

Correct Answer: D

Rationale: Hypoplastic left heart syndrome leads to early heart failure due to an underdeveloped left ventricle and systemic hypoperfusion.

Correct Answer: B

Rationale: Magnesium sulfate administered antenatally is primarily used to reduce the risk of cerebral palsy in preterm infants, as it provides neuroprotective effects.

Correct Answer: D

Rationale: Nebulized adrenaline is commonly used in croup to reduce airway edema, improving airflow and reducing respiratory distress.

Correct Answer: D

Rationale: Dennie-Morgan folds are characteristic infraorbital creases seen in children with atopic dermatitis or allergic rhinitis.

Correct Answer: A

Rationale: The mechanism of corticosteroids is well understood; they modulate immune response by suppressing inflammation through inhibition of cytokines and prostaglandins.