The graph of the first derivative f' of a function f is shown in the figure below. y = f'( x ) -2 0 2 4 8 x (a) On what interval(s) is f decreasing? (b) On what interval(s) is f concave down? (A) (0, 9) (B) (1, 6), (8, 9) (C) (0, 1), (6, 8) (D) none (E) (0, 2), (3, 5), (7,9) (F) (2.5, 4), (6,9) (G) (0, 2.5), (4, 6) (H) (2, 3), (5, 7) Select v | | Part (a) choices. (A) (0, 2.5), (4, 6) (B) (2, 3), (5, 7) (C) (0, 9) (D) (1, 6), (8,9) (E) none (F) (2.5, 4), (6,9) G) (0, 2), (3, 5), (7,9) (H) (0, 1), (6, 8) Select v | + Part (b) choices