Let p and q be twice-differentiable functions on (0,4) such that p′′(x)<q′′(x) for all x in (0,4). Which of the following best compares the concavity of the graphs of p and q on (0,4)?
a) The graph of p is more concave up than the graph of q on (0,4).
b) The graph of q is more concave up than the graph of p on (0,4).
c) Both graphs have identical concavity on (0,4).
d) Both graphs are concave up on (0,4).