In a form, user have an option to choose the submission type. Based on the selected submission type, user should get an option to choose sub-type. Please let me know how this is done in Drupal 7. Please suggest a module.
If user select e-book, sub-type should change to case:1 (see image)
If user select e-project, sub-type should change to case:2
If user select e-lab manual, sub-type should change to case:3