A farmer wants to build a pen for his sheep. One side of the pen will be a river. The sheep need about 2000 m2 of area to graze. About what length (x) and width (y) should the organization use to use the LEAST amount of fencing possible?

Alength = 43 m, width = 46 m

Blength = 50 m, width = 40 m

Clength = 63 m, width = 32 m

Dlength = 100 m, width = 20 m