In my country, there are districts in each city.
I have set my city a drop down menu. What I want to add is another sub drop down list when you choose a specific city.
For example: there are city a, b, c and each city has different districts like: a1, a2, a3, ba, bb, bc, and c11, c12, c13

So when you list a product, I want them to choose city from the drop down. If they choose city a, then another drop down show up as: a1, a2, a3.
For if they pick city b, another drop down follow as: ba, bb, bc.

This is the best way to make it so ppl can find the ads near the place they are able to go.

Is this possible to do?

Thank you