Some food is placed in a freezer. After t hours, the temperature of the food is dropping at the rate of r(t) degrees Fahrenheit per hour, where r(t) = 12 + 4/(t + 3)².

(a) Compute the area under the graph of y = r(t) over the interval 0 ≤ t ≤ 2.

(b) What does the area in part (a) represent?