If a copper block was initially (5.2° C) and is dropped into a beaker of (H₂O) that was initially at (23.1° C), what is the change in temperature for the metal if the final temperature of the water was found to be (2.5° C)?

a. (15.6° C)
b. (18.3° C)
c. (20.6° C)
d. (25.7° C)