A highly cohesive work groupis a prerequisite for high team performance. Sociologists point that the association between group cohesion and success is owing to the support individual team members give to one another and their acceptance of the group's goals and activities. Each of the following, if true, either provides support for or cannot weaken the sociologists’ assumption aboutthe relationship between cohesive and success EXCEPT.

The given statement implies that a team's success is due to the bonding and support team members extend to each other. A good camaraderie between the workers and healthy environment of human bonding goes a long way in ensuring success. 

We have to find a statement which weakens this statement. This is done by option A which, if true, changes the needle of a team's success from tam members supporting each other to the dominance and authority established by the group leader. Option A turns the given statement on its head and hence, weakens it greatly.