18
Step-by-step explanation:
n! = n * (n-1)!
For example 7! can be written as 7 * 6!
3! is 3* 2!
6! is 6 * 5!
Cancel out 5! from the top and bottom . Also cancel out 2! from top and bottom.
3*6= 18
the answer is B,A,C,A