Strange, because it sounds a bit like Indian English. I bet "These people laugh very less" will be accepted. I have not tried it though.
My suggested "correct" answer was "These people laugh TOO less"!!! (I had written "these people laugh much less").
No because only one sentence is being programed by the company even it is wrong or right we have to pick the same one.
Then the sentence wouldn't need the बहुत . I think you have to include "very" or "a lot" or "much" in your translation, for the बहुत .
Are "These people rarely laugh" and "These people hardly laugh" acceptable?
One would think so. But it relies a lot on context, which we don't have in these exercises.
It is difficult for them to program it to every possible vague translation. The most direct is always better. I don't see a word for "rarely" there, but I do see the words for "very" and "less/little"