To Study Circadian Rhythms in European Hamsters, Researchers Measured MRNA

To study circadian rhythms in European hamsters, researchers measured mRNA levels for two clock genes (Per2 and Bmal1) in individuals who were not hibernating, and therefore had normal body temperature and individuals who were hibernating, and therefore had lower-than-normal body temperature. Both sets of individuals were kept in total darkness. The results are shown in the figure. Which statement is best supported using the data?

A) At night, during euthermia, there is more Per2 RNA in the hamster than Bmal1 RNA.
B) During hibernation, the clock genes are regulated differently than during euthermia.
C) The Bmal1 gene is only expressed at night during hibernation.
D) The metabolic rate of the hamsters increased during hibernation.