Which of the following pairs of statements could correspond to a curve that is decreasing and concave up? Select one: O a. f'(x) = -1 and f"(x) = -16 O b. f'(x) = 3 and f"(x) = -2 O c. f'(x) = 5 and f"(x) = 5 O d. f' ( x ) = - 2 and f" (x) = 7