Allergic reaction.

Choice A rationale:

Transfusion-related acute lung injury (TRALI) usually presents with acute respiratory distress, not urticaria, pruritus, and flushing.

It is characterized by the sudden onset of dyspnea, hypoxemia, and pulmonary edema.

Choice B rationale:

Bacterial contamination of blood products can lead to sepsis, but the symptoms described in the question (urticaria, pruritus, and flushing) are not indicative of bacterial contamination.

Symptoms of bacterial contamination would typically include fever, chills, and signs of infection.

Choice C rationale:

Febrile nonhemolytic reactions can cause fever, chills, and rigors, but they are not associated with urticaria, pruritus, or flushing.

Choice D rationale:

An allergic reaction, also known as a hypersensitivity reaction, can manifest with symptoms like urticaria (hives), pruritus (itching), and flushing.

These symptoms are indicative of an allergic response to components in the blood product, such as plasma proteins or allergens.