A 15-month-old male child with failure to thrive, diarrhea, and fatty stool. Of the following, the MOST common possible cause of his illness is

Correct Answer: A

Rationale: Malabsorption is the leading cause of failure to thrive with diarrhea and fatty stools, often due to celiac disease or other digestive disorders. Intestinal parasites and milk protein intolerance are less common causes in this age group.

Correct Answer: B

Rationale: Thrombocytosis is not commonly associated with serum sickness, whereas inflammation markers like ESR and reduced C3 are expected.

Correct Answer: B

Rationale: Yellow jackets are highly aggressive and responsible for the majority of insect sting-related allergic reactions due to their frequent and painful stings.

Correct Answer: A

Rationale: Dilated cardiomyopathy results in impaired contractility, leading to heart failure and chamber dilation.

Correct Answer: D

Rationale: Poliomyelitis causes asymmetric, flaccid motor paralysis without sensory loss, as it primarily affects anterior horn cells.