Solve the Problem $x$ Will the Area of the Cross Section Be a Maximum

Multiple Choice

Solve the problem.
-A piece of rectangular sheet metal is 4 inches wide. It is to be made into a rain gutter by turning up equal edges to form parallel sides. Let x represent the length of each of the parallel sides. For what value of $x$ will the area of the cross section be a maximum (and thus maximize the amount of water that the gutter will hold) ? If necessary, round to 2 decimal places.

A) 8 in.
B) $16 \mathrm { in }$ .
C) 1 in.
D) 2 in.