The layer of the interior where the temperature drops from 7,000,000C to 2,000,000C is

A. core

B. radiation zone

C. convection zone

Within the composition of stars, there are a number of distinct zones with different regimes of behavior. In the case of the Sun, the temperature profile listed above equates to that of the radiation zone, where the temperature falls over 5 million degrees Celsius. Thus the answer is B. radiation zone.