RE: how i created Dropdown list?
If the dependent optionset does not work for you then we can do a separate JS solution.
In the first dropdown you would have values such as
1 - Option 1
2 - Option 2
3 - Option 3
In the second drop down you would have values such as
101 - Option A for 1
102 - Option B for 1
201 - Option A for 2
...
You can then on the change event of first optionset, remove the unnecessary values from second option set.
The only issue here, is that if you select Option 1, and you made a mistake and want to select option 2, you are not going to be able to, since you already removed the data, so on the first selection, you will need to "backup" your optionset data into an object/array/json...
Let me know if you need additional help.