Areas, Finite Sums, and Limits of Finite Sums - Lecture 15 (Calculus 1)

When approximating the area under a curve with rectangles, what does an "upper sum" use for the height of each rectangle?

1. A.The leftmost x-value of the subinterval
2. B.The rightmost x-value of the subinterval
3. C.The maximum value of the function on each subinterval
4. D.The average of the function's values at the two endpoints of the subinterval