You are assessing a man with suspected hypothermia. the patient is conscious and alert, and is actively shivering. his respiratory rate is increased, but his breathing is unlabored, and the pulse oximeter reads 72%. the pulse oximetry reading is most likely:

the pulse oximetry reading is most likely secondary to decreased perfusion in the extremities.

The patient has no abnormality in breathing beside increased rate so there shouldn't be any issue in oxygen level. 

When your body exposed to cold, the body will respond by constricting peripheral blood vessel. By doing so the body will prevent further heat loss because the blood is not exposed to the cold extremities. But it will reduce blood perfusion in your extremity, therefore the oxygen level might be reduced.