Is it possible to combine for separate grouped field options under 1 dropdown?

I need to combine 4 separate drop down sections into 1 and make it required. How do I add another "question" into this new larger drop down section.

Here is the form I'm talking about. formID=52144134769962

Rob

It seems to me that based on what you are saying you want to have 4 different sections within 1 single dropdown but each are grouped inside of that singular dropdown perhaps?

I looked on your form link you provided above but I don't see any dropdowns.

Are you looking to convert the 4 checkbox option groups into this? Or?

I would suggest taking a look at these widgets which you may find useful:

http://widgets.jotform.com/widget/grouped_values_dropdown 

http://widgets.jotform.com/widget/dynamic_dropdowns