Answer:
coercive
Step-by-step 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.