Afree rider is a member of a group who contributes a lot member of a group who contributes little member of a group who contributes on par with other team members member of a group who contributes only during the time of a need

I believe the answer is: . member of a group who contributes little

While contributes very little to the group, free rider still obtain the positive benefit of the group's work result like any other members.
The chance of free rider to exist would increase as the group become larger and took in more members

Supreme court ! hbdbsbbs