Multi lever Radio or Dropdown Field

I was searching for information on how to establish a multi-level radio or drop-down field. Here is my objective:

A member may be able to select from one certification field the following :

1. driver
a. auto
b. straight job
c. truck
d trailer

2. Instructor
a. car
b. boat
c. planes
d. train

3. MD
a. internal medicine
b. cardiology
c. surgeon
d. EANT

4. Navigator
a. plane
b. boat
c. train


These are just examples, can I do this in one field as there are more the 20 certifications and I do not want to create one field for each one, would prefer radio buttons but multiple select drop-down would work (these can be lengthy to scroll).

Thank you.

Create a select field and use the Group parameter to group them. You can either use a multi-select field to allow multiple selections or use a select field inside of a Field Group field. Example as follows with Group parameter.

Value: Driver
Group: Yes

Value: driver_car
Label: Car

Value: driver_truck
Label: Truck

Value: Instructor
Group: Yes

Value: instructor_car
Label: Car

Value: instructor_truck
Label: Truck

You can't use groups for radio or checkbox fields.

Thank you Kyle will try.