How do you limit choice of option in checkbox?

I would suggest to use radio button instead of checkbox if you are requiring user to select only one option. Radio button options already limited to single selection every-time.

In Check boxes also, it is possible, to limit the maximum or minimum required number of options. For doing this, right click the check box field, show properties then you can see these options.

You can also check the below guide, which explains the same thing in more detail.

https://www.jotform.com/help/251-How-to-set-up-minimum-or-maximum-number-of-selection-on-Checkbox-Field