I think this can be done with only Javascript and not to be applied in LS core by default , but just a attribute plugin system.

Because next time another user want

• this one : http://loudev.com/
• this another one : http://ivaynberg.github.io/select2/#multi

etc ....

PS: All can be done in template and some script in question text.

For your recommendation to work, the multiple choice option has to be rendered as a <select> with <option>'s... right now it's rendered as an unordered list

and
• - what do I need to change in order for the multiple choice list to be printed using <select> and <option> in html?

You can allways update HTML with jquery, and after apply select2 (for example).

I don't say it's a bad idea, i just say it must be a Question attribute plugin and not in core system.