The correct option is C 30, 60
Multiples of 5:
5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65.....
Multiples of 6:
6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66......
Multiples of 10:
10, 20, 30, 40, 50, 60, 70.......
30, 60.....are common multiples of 5, 6 and 10.