On a coordinate plane, a parabola opens down. It goes through (negative 2, negative 2), has a vertex at (1.5, 10), and goes through (5, negative 2).
Over which interval is the graph of f(x) = –x2 + 3x + 8 increasing?

(–∞, 1.5)
(–∞, 10.25)
(1.5, ∞)
(10.25, ∞)