Select the option that expresses the given sentence in active voice.

The thieves were caught by the police.

The police caught the thieves.

The correct option that expresses the given sentence in active voice is The police caught the thieves.

The other options are incorrect because:

• The police was caught the thieves is grammatically incorrect. The subject of the sentence is "the police," which is a plural noun. The verb "caught" is singular.
• The police were caught the thieves is also grammatically incorrect. The verb "caught" is singular, but the subject of the sentence is plural.
• The police had caught the thieves is in the past perfect tense, while the original sentence is in the simple past tense.