The area of each book is 63 in2. the height of the stack is 15.75 inches. what is the volume of the stack of books? a) 337.85 in3 b) 665.21 in3 c) 850.15 in3 d) 992.25 in3

We know that

[the volume of the stack of books]=[area of each book]*[height of the stack]
area of each book=63 in²
height of the stack=15.75 in
so
[the volume of the stack of books]=[63 in²]*[15.75 in]=992.25 in³

the answer is 
D)992.25 in³

I'm sure the answer is a