I don't think you can do exactly that. It is, bascially, a trick question.
If you want to engage in that sort-of trickery, then you probably can do something effectively the same using one of the built in question types, but the exact form would have to be different. You will need to get creative.
(But, it is a made a bit tricky by the fact that Moodle tries hard to stop students from accidentally forgetting to answer part of the question, so it will warn about parts of the question that are left blank, which is not what you want.)
If you want to engage in that sort-of trickery, then you probably can do something effectively the same using one of the built in question types, but the exact form would have to be different. You will need to get creative.
(But, it is a made a bit tricky by the fact that Moodle tries hard to stop students from accidentally forgetting to answer part of the question, so it will warn about parts of the question that are left blank, which is not what you want.)