2011 AMC 10A Problem 9

A rectangular region is bounded by the graphs of the equations y=a, y=-b, x=-c, and x=d, where a,b,c, and d are all positive numbers. Which of the following represents the area of this region?

\textbf{(A)}\ ac+ad+bc+bd\qquad\textbf{(B)}\ ac-ad +bc-bd\qquad\textbf{(C)}\ ac+ad -bc-bd \quad\quad\qquad\textbf{(D)}\ -ac-ad +bc+bd\qquad\textbf{(E)}\ ac-ad -bc+bd

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.