A continuous function q is positive and concave down on the interval [0,4]. A trapezoidal approximation with two subintervals of equal length gives an estimated average value of 6 for q on this interval. Which of the following statements about the true average value of q is most appropriate?
a) It is less than 6.
b) It is equal to 6.
c) It is greater than 6.
d) It cannot be determined from the information given.