Mr. Carter is building a circular fire pit in his backyard. The diameter of the fire pit is 6 feet and he will fill the interior with gravel covering 5/6 of the area. How much gravel will he need?
A. 23.55 sq. ft.
B. 28.26 sq. ft.
C. 94.2 sq. ft.
D. 113.04 sq. ft.