Let me try it..............
(1) x is a multiple of 6 & 9;
i.e., x is a multiple of 18;
i.e., x = 18m & y = 14n (since y is a multiple of 14)
i.e., xy = 252mn or 252k (m,n,k are any positive integers)
For k =1, 2, 3, 4 etc; xy is not a multiple of 105
Whereas for k=5, xy is a multiple of 105 ---> INSUFF
(2) y is a multiple of 14 & 25;
i.e., y is a multiple of 350; [14×25]
i.e., x = 6m & y = 350n (since x is a multiple of 6)
i.e., xy = 2100mn or 2100k (m,n,k are any positive integers)
2100 is divisible by 105 ... hence xy is a multiple of 105 ...
SUFFICIENT
Answer is B. | 
