Subject-verb agreement is when the subject and the verb agree with each other in terms of number. The subject and the verb should either both be plural, or both be singular. In this case, the "dogs" are the subject and "are" is the verb. When you have "dogs" in plural, you have to use the plural verb, which in this case is "are". The other choices do not agree in terms of verb and subject agreement. Hope this helps :)
