If X is a multiple of 6 then X has 2 and 3 as prime factors
If Y is a multiple of 14 then Y has a 2 and a 7 as prime factors
So XY has atleast a 2,3,2, and 7 as prime factors
105 has 5 3 and 7 as prime factors 5*3*7=105
So for XY to be a multiple of 105 XY must have a 5, a 3, and a 7 in its factorization. There is a 3 and a 7 but no 5.
A 5 in XY's factorization is necessary for XY to be a multiple of 105.
(1) If X is a multiple of 9 then X's factors are 3 and 3 as well as 2 and 3 (from the info in the question).
We don't know if XY also has a 5 as its factor. so (1) alone is insufficient.
(2) If Y is a multiple of 25 then Y's factors are 5 and 5 as well as 2 and 7 (info in the question).
So, we know for sure that 5 is a factor of XY. (2) is sufficient.
So the answer is (B)
