Ten years ago, a school with a fixed population decided to increase the size of its student body. The size of the students body t years since the increase began as S(t). It is known that the value of the definite integral from 0 to 10 years of S ' (t) is 400. Which of the following is true? O A. The student body grew by 400 students O B. The student body is now at 400 O C. we add a C in the answer O D. The student body is increasing by 400 per year O E. Nothings can be determined from this information