A bakery is creating a round cake with three different levels as shown below. The diameters of the three cakes are 10 in, 8 in, and 6 in. The cakes are stacked and centered on top of each other with the largest cake on the bottom and the smallest cake on top. In order to plan the decorations for the cake, the bakery needs to determine the total exposed area available for decoration on the top faces of the three cakes (the sides of each cake will not be decorated). What is the total exposed area, in square inches, of the top faces of the three cakes?

A
25π in2

B
50π in2

C
100π in2

D
200π in2