Select the option that expresses the given sentence in passive voice.
The police had collected the primary evidence before they arrested the culprit.
1
The primary evidence had been collected by the police before the culprit was arrested.
2
The primary evidence might have been collected by the police before the culprit was arrested.
3
The primary evidence was collected by the police before the culprit was arrested.
4
The primary evidence had collected by the police before the culprit was arrested.