David is keeping track of the internal temperature of a chicken he is cooking. The table below shows how its temperature is a function of the time it has been in the oven. Which of the following gives the average rate that the temperature is increasing at from 15 to 45 minutes? (A) 2.1 F per minute
(B) 2.4 F per minute
(C) 2.8 F per minute
(D) 3.2 F per minute