The surface of the square pyramid is:
one square with a side length of 18 inches
four triangles with a base length of 18 inches and a height of 16 inches.
The area of a square: \(A_\boxed{ }}=18^2=324\ in^2\)
The area of a triangle: \(A_\Delta=\dfrac{18\cdot16}{2}=144\ in^2\)
The surface area of the pyramid is:
\(SA=A_\boxed{ }}+4A_\Delta\\\\SA=324+4\cdot144=900\ in^2\)
Answer: B. 900 square inches.
