Approximately 90% of youths who complete suicide have a preexisting psychiatric illness. Of the following, the MOST commonly encountered illness is

Correct Answer: A

Rationale: Major depression is the most common psychiatric illness associated with completed suicides in youths.

Correct Answer: D

Rationale: Milrinone is a phosphodiesterase inhibitor used for chronic heart failure rather than acute shock management.

Correct Answer: A

Rationale: Oral food challenges are the gold standard for diagnosing food allergies.

Correct Answer: D

Rationale: A foreign body in the left main bronchus leads to air trapping on the left side, causing hyperinflation and shifting the mediastinum to the right on expiration. This results from a ball-valve effect, where air enters but cannot exit fully.

Correct Answer: A

Rationale: Dilutional hyponatremia occurs when there is excessive water retention relative to sodium. Conditions like heart failure cause fluid overload, leading to a dilution of serum sodium.