Here is the graph of the derivative of a function f(x), whose domain is the open interval (5, 5). Answer the following questions. Explain your answers briefly. (a) At what x-value does the function f(x) have an extremum? Is it a local maximum or minimum? (b) At what x-value does the function f(x) have a point of inflection? (c) State the interval(s) where f(x) is concave up and down?