How many smallest number moves need to measure 6 liter of water?

Question

You are given two (unmarked) containers of capacity 9 liter and 4 liter and a huge tank of water. Need is to get measure of exactly 6 liter, of water. A move is either filling a container completely or emptying a container (either fully or partly). The smallest number of moves needed to do this task is?

Answer options:
A. 8
B. 10
C. 12
D. 15

Please explain your solution step by step.
Thanks for your help.

Answer 1

1. Fill 9
2. Fill 4 from 9
3. Empty 4
4. Fill 4 from 9 again
5. empty 4
6. Put remaining liter from 9 in 4
7. fill 9
8. Fill 4 from 9