Traffic Followers, a group promoting road safety, has a strict code of sanctioning members found in violation of the traffic rules. In some cases, nonconformity can result in expulsion from the group. This is an example of a group exercising power over its members.

coercive

Explanation:

coercive power is the capability to force any one to follow any order even if he is not willing to follow that order. This power is exercised via use of punishment mechanism i.e if anyone disobeys the order he will be penalized , penalty  is pre-decided one.

Generally coercive power is used in cases where it is observed that majority of people will not follow the rules and regulation consciously

In the problem stated above group members are asked to follow the traffic rules and if they don't follow it they can expelled from group.  Expulsion is here deterrent and the traffic rule enforced upon the group members and it can be safely concluded that coercive power is being used here.

the number of senators, and representatives, the state has in congress.