Upon Opening a Shipment of Vaccines, the Technician Notices the Boxes

Upon opening a shipment of vaccines, the technician notices the boxes state "Keep Cool" on their labels. Since the technician knows how sensitive vaccines can be to heat, she places them promptly in the freezer. In what temperature should the vaccines have been placed?

A) Less than 8° C
B) Greater than 8° C but lower than 15° C
C) Greater than 15° C but lower than 30° C
D) Greater than 40° C