IN this question we have to find all the pairs out of the four given options , whose least common multiple is 18 .
The first pair is 2 and 6, and for this pair, the common multiple is 6.
For the second pair 3 and 6, whose common multiple is 6 .
For the third pair 2 and 9, the common multiple is the product of them , that is 2 times 9 which is 18.
For the last pair, which is 6 and 9, the least common multiple is 18 .
So the correct options are C and D .
