A Patient Transfused with 2 Units of Packed Cells Spiked

A patient transfused with 2 units of packed cells spiked a fever of 99.5°F and complained of chills 3 days after transfusion. The DAT was positive with polyspecific antisera and anti-IgG but negative with anti-C3d. Compatibility testing was performed on the pre- and post-transfusion specimens. The latter was incompatible with one of the donor units transfused. An antibody screen was done on both the pre- and post-transfusion specimens. An antibody was detected in the post-transfusion specimen only and identified by panel studies as anti-Jk^a. This transfusion reaction is most likely caused by:

A) an anaphylactic response.
B) delayed hemolytic transfusion reaction (DHTR) caused by anamnestic response.
C) DHTR caused by primary alloimmunization.
D) post-transfusion purpura.