The following statements concerning the location of an extreme value of a twice-differentiable function, f, are all true. which statement also includes the correct justification? (a) the function has a maximum at x=5 because f'(5)=0. (b) the function has a maximum at x=5 because f'(x)< 0 for x< 5 and f'(x)> 0 for x> 5. (c) the function has a minimum at x=3 because the tangent line at x=3 is horizontal. (d) the function has a minimum at x=3 because f'(x)< 0 for x< 3 and f'(x)> 0 for x> 3. (e) the function has a minimum at x=3 because f"(3)< 0.