Which of the following options is the correct value of z if the greatest common divisor of (z-1)!,(z+2)!, and (z+4)! is 120.  Select the correct option.
A) 9  B) 5  C) 6  D) 7  E) 8
GCD of (z-1)!,(z+2)!, and (z+4)! is 120. Find z.   Best way to find n is substitute each of the answer and find out the correct one.   Only option C gave the correct answer.   Option C: 6 and find GCD or 5!, 8! and 10!. 5! itself is 120 and 5! which is contained in the other two factorials. This satisfies the condition, hence answer is 6.   Answer is 6.
<result>C</result>
Which of the following options is the correct value of z if the greatest common divisor of (z-1)!,(z+2)!, and (z+4)! is 120.