**Core Concept**
TRALI (Transfusion-Related Acute Lung Injury) is a serious complication of blood transfusion characterized by non-cardiogenic pulmonary edema, typically occurring within a specific time frame after transfusion. It is a leading cause of transfusion-related mortality in critically ill patients.

**Why the Correct Answer is Right**
TRALI occurs due to the transfusion of plasma-containing blood products, particularly in patients with pre-existing lung injury or inflammation. The pathophysiology involves the activation of neutrophils and endothelial cells by the transfused plasma, leading to increased vascular permeability and non-cardiogenic pulmonary edema. The timing of TRALI is crucial, as it typically occurs within 6 hours of transfusion.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because TRALI is not limited to a specific time frame, but rather typically occurs within 6 hours of transfusion.
**Option B:** This option is incorrect because TRALI is not exclusively related to the transfusion of packed red blood cells, but rather any plasma-containing blood product.
**Option C:** This option is incorrect because TRALI is not a direct result of the transfusion of platelets, but rather the plasma component.

**Clinical Pearl / High-Yield Fact**
It is essential to recognize that TRALI can occur in patients who have received a single unit of blood, highlighting the importance of monitoring for signs of TRALI, even after a single transfusion.

**Correct Answer: C. 6 hours**