Definition: The AREA A of the region S that lies under the graph of the continuous function f is the limit of the sum of the areas of approximating rectangles

(a) Use the above definition to determine which of the following expressions represents the area under the graph of

** A. ** ** B. ** ** C. ** ** D. **

(b) Evaluate the limit that is the correct answer to part (a). You may find the following formula helpful:

Value of limit =

You can earn partial credit on this problem.