Just as you are arriving at the emergency department bay, your patient, on whom you started an IV at the scene, complains of sudden chills, back pain, and nausea. The patient appears flushed, and his skin is hot and moist to the touch. Which of the following most likely accounts for your patient's presentation?

A) Pulmonary thromboembolism
B) Pyrogenic reaction
C) Circulatory overload
D) Anaphylaxis

B