The incorrect verb is "have", and should be replaced with "has". The Cedarburg Environmental Association has worked for decades with one clearly defined goal to reduce the negative impact of human activity on the natural world.
Explanation:
A subject-verb agreement means the subject and verb must correspond with each other. If the subject is plural, the verb must also be plural, and the same applies to if the subject is singular. In this case, the subject (The Cedarbug Environmental Association) is singluar, since they are referring to the assicoation as a whole. Therefore, the verb must also be singular. "Have" is plural; "has" is singular. I hope this helps!
