Multiple dependant drop downs

Hello everyone and thanks in advance for your help. This is my first post and I will really apreciate a hand.

Im breaking my head trying to do 3 dependant drop down menus. When you select the first one a list of options will apear on the second one and after you select the second one, a list will update on the third.

I'm attaching a file to make my self clear.

thanks in advance for your help