You should not attempt to actively rewarm a patient with moderate or severe hypothermia in the field because:

A) the risk of inadvertently inducing hyperthermia is too high.
B) rewarming too quickly can cause a fatal cardiac dysrhythmia.
C) it is painful for the patient and you cannot give analgesic drugs.
D) active rewarming has been shown to cause severe hypertension.

Answer: B) rewarming too quickly can cause a fatal cardiac dysrhythmia.