The correct option is D 30
Let us first list down the multiples of 6 and 10.
Multiples of 6 are 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, ... and so on.
Multiples of 10 are 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, ... and so on.
Common multiples of 6 and 10 are 30, 60, 90, ... and so on.
Since 30 is the smallest of them, it is the least common multiple (LCM) of 6 and 10.