The function f is continuously differentiable on the interval [−5,8], with f′(−5)=−7.889 and f′(8)=−14.25.
What can you say about the existence of a zero of f on [−5,8] ?
A. The function has at least one zero on [−5,8].
B. Nothing.
C. The function has two zeros on [−5,8].
D. The function has a unique zero on [−5,8].
E. The function has at most one zero on [−5,8].