Which blood product is collected through apheresis?

The correct choice is platelets, as they are specifically collected through a process called apheresis, which is a method that separates blood components using a machine. During apheresis, blood is drawn from the donor and processed to collect specific components, in this case, platelets, while returning the remaining blood back to the donor. This allows for the collection of larger quantities of platelets than would be obtained from whole blood donation.

Whole blood, packed red blood cells, and serum do not require apheresis for their collection. Whole blood is collected as a complete unit without separation, while packed red blood cells are derived from whole blood after its components have been separated, typically using centrifugation. Serum is the fluid portion of the blood that remains after coagulation and is usually obtained from clotted samples rather than through the apheresis process. Thus, the unique collection method of platelets through apheresis highlights why this option is correct.