The students in a third-grade classroom arranged the desks in this shape.
A shape is shown with one side labeled 12 in., two sides labeled 6 in., four sides labeled 3 in., and one side labeled p.
The perimeter of the shape is 42 feet. What is the length, in feet, of the side labeled p?
A.
4
B.
6
C.
24
D.
36