Surface area of a square pyramid
= area of the base + 4 times area of one of the slanted faces
Area of the base = side length * side length = 18*18 = 324
Area of one slanted face = (1/2) * side length * slant height = 1/2*18*19 = 171
Surface area = 324 + 4 * 171
= 1008 in.2
ans is C