I was trying to be serious.
You can make it so that a student cannot click Next until the student has selected an option. (Well, Moodle does not really have that option, but one could imagine it.)
Surely you have encountered forms like this yourself, when trying to get on with some task online. Some form that insists you type something in a box before you can continue. Do you give the question careful consideration, and type a well thought-out response? I certainly don't. I just type a . character or an x or something, just so I can move on.
Surely you don't expect your students to behave any differently. If they don't want to answer, and you force them to selected one of the options, they will just click one at random. Encouraging this sort of thing has always struck me as pointless.
There is already a good extrinsic incentive to for the student carefully consider the question and to try to give the right answer: if you get it right you get a mark, and if not you don't. Hopefully there is also an intrinsic incentive: the questions are interesting, and trying to answer them helps the students learn.