Let g be a function such that g(-1) = 0 and g(2) = 5. which of the following conditions guarantees that there is an x, -1 < x < 2, for which g(x) = 3 ?
a) g is continuous on [-1, 2]
b) g is differentiable on (-1, 2)
c) g is increasing on [-1, 2]
d) g is concave up on (-1, 2)