how to make dynamic form

Question

I am having a status Field which has 3 options 1)activated 2)rejected 3)pending.If user select rejected status then he has to enter reason for rejection else that reason field should be hidden.Or when user choices rejected i should redirect it to some other form so that i can send email using the rejection reason

Answer 1

Here are some helpful links

B-list post about it

The Uswaretech post about it