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

He ordered the police to pursue the robber and his gang.

The police were ordered to pursue the robber and his gang.

The correct passive voice of the given sentence is The police were ordered to pursue the robber and his gang.

The active voice of the sentence is He ordered the police to pursue the robber and his gang. This sentence is in the simple past tense, which is used to describe an action that happened in the past. The passive voice of the sentence is formed by putting the subject of the active sentence after the verb "to be" and the past participle of the main verb. In this case, the subject of the active sentence is "he" and the main verb is "order." The past participle of "order" is "ordered." So, the passive form of the sentence is The police were ordered to pursue the robber and his gang.

The other options are incorrect because:

• Order the police to pursue the robber gang. is in the imperative mood, which is used to give commands or make requests.
• Pursue the robber and gang were the orders by police. is a jumbled sentence that does not make sense.
• The robber and gang were pursued. is in the passive voice, but it does not specify who ordered the pursuit.
• Pursue the robber and gang. is the active voice of the original sentence, not the passive voice.