On a coordinate plane, a parabola opens up. It goes through (negative 8, negative 2), has a vertex at (negative 5, negative 6.5), goes through (negative 2, negative 2), and has a y-intercept at (0, 6).
Over which interval is the graph of f(x) = one-halfx2 + 5x + 6 increasing?

(–6.5, ∞)
(–5, ∞)
(–∞, –5)
(–∞, –6.5)