The correct answer is D. Have.



1. Understanding the Subject:
- The police: This is a plural subject. Even though "police" refers to a single organization, it is treated as a plural noun in terms of subject-verb agreement.

2. Verb Agreement:
- Were: While "were" is a plural verb form, it is not typically used with "police" in this context.
- Has: This is a singular verb form and does not agree with the plural subject "police."
- Was: This is also a singular verb form and does not agree with the plural subject "police."
- Have: This is the correct plural form of the verb that matches the plural subject "police."

3. Grammar Rule:
- Subject-Verb Agreement: When the subject is plural, the verb should also be plural. Since "police" is treated as a plural noun, the verb must be in the plural form "have."

Summary:
- "Have" is the correct choice because it agrees with the plural subject "The police." The correct sentence is: "The police have arrested the suspects."