A function g is differentiable, increasing and concave upward on the interval [1,4]. Let ms be the slope of the secant line through (1,g(1)) and (4,g(4)), and let mt be the slope of the tangent to the curve at some point c with 1<c<4. Which of the following is necessarily true?
a) mt>ms
b) mt=ms
c) No definite relation between mt and ms
d) mt<ms