Ans:- Let us find the positive divisors and their product in each case:
(A) Divisors of 8 (not including the number itself): 1,2,4. Product= 8.
(B) Divisors of 15 : 1,3,5. Product= 15.
(C) Divisors of 18 : 1,2,3,6,9. Product= 324. Seems to be the correct answer.
(D) Divisors of 21 : 1,3,7. Product= 21.
(E) Divisors of 27 : 1,3,9. Product= 27.
Notice that number of factors for each of the option (A), (B), (D) & (E) are 4 (including the number itself) and these do not satisfy the question’s condition. The correct answer is with Option (C) 18 that has 6 factors.