Conditional drop down lists/menus

I can’t find a way to do conditional drop-down lists.

All I want is to have 3 lists, A, B and C. When someone clicks on an item in A then there is a list of options in B. The options in B would change depending on which option they selected in A.

I have tried Caldera forms and it doesn’t seem to be able to do it – or I am using it incorrectly.

Anyway, can someone point me in the right direction please?

Thanks