Context: Scientists in a laboratory were working with insulin, a protein often used to treat diabetes. They left two identical vials of insulin in different places. This table shows how the temperature of each vial changed over 15minutes.
During this time, thermal energy was transferred from () to ().
A. each vial . . . the surroundings
B. the surroundings . . . each vial
Answer with the option's letter from the given choices directly.

B