The Clinic Nurse Is Checking the Potency of the Vaccine

The clinic nurse is checking the potency of the vaccine. Which finding may have rendered the vaccine ineffective?

A) The vaccine was frozen as labeled.
B) The vaccines have been stored in a refrigerator where the temperature has been maintained between 35^° to 46^° F.
C) The vaccine's expiration date expires within the next month.
D) The vaccine is stored in the door of the refrigerator.