Jill has 120 feet of fencing to use for her horse paddock. To increase the area she can enclose, she plans on using the side of the barn as one side of her paddock as shown in the picture.

Determine which equation can be used to find the dimensions of the horse paddock when the area is 1,800 square feet. Let x represent the width of the paddock.

A. -x^2 + 120x = 1,800
B. 2x^2 − 120x = 1,800
C. -2x^2 + 120x = 1,800
D. x^2 − 120x = 1,800