The quiet kid in the group project probably has the best idea. Ask them directly and then actually wait.

Groups reward speed of speech rather than quality of thought, so the fastest talker sets the direction and everyone else adjusts to it. Someone who processes before speaking often has the better idea and no route into the conversation, because by the time it is formed the group has moved on. The silence is not an absence of opinion.

Ask them directly and by name, then leave the pause alone. Three or four seconds will feel much longer to you than to them. Filling that gap with another question is how most good ideas get lost.