A continuous function h is increasing on [0,1] and decreasing on [1,3]. The interval [0,3] is divided into three subintervals of length 1. Let L and R denote, respectively, the left and right Riemann sums that use these subintervals to approximate ∫03h(x)dx. Which statement about L and R is necessarily true?
(a) L is an underestimate and R is an overestimate.
(b) L is an overestimate and R is an underestimate.
(c) Neither L nor R is guaranteed to be an overestimate or an underestimate.
(d) L and R are both underestimates.