What exactly do you mean by *? Like exponent? If so the domain is R= −∞,∞ with its range being [−1,1]. If this wasn’t meant by exponent, please comment and I’ll reply ASAP!
The answer is: 
By definition, a point is a local minimum if it has the smallest <em>y</em> coordinate in that interval and the graph goes from decreasing to increasing.
Based on this information, you can graph the points given in the problem above, as you can see in the figure attached. Then, you can notice that the ordered pair that is closest to a local minimum of the function is the last option shown in the problem.
13.13? If it is, it would be 91.91. If it's really 1313 you would need 9191 cups.