The Main Difference Between Social 'Loafing' and 'Free-Riding' Is That

The main difference between social 'loafing' and 'free-riding' is that:

A) although loafers reduce effort on a co-active task, they still contribute to the group product; whereas free riders exploit the group product while contributing nothing.
B) although free riders reduce effort on a co-active task, they still contribute to the group product; whereas loafers exploit the group product while contributing nothing.
C) although loafers increase effort on a co-active task, they do not contribute to the group product; whereas free riders assist the group product and contribute a great deal.
D) free riders increase effort on a task with no expectation of receiving a reward, whereas loafers do not assist with the task and expect all the benefits.