Q:

In the following questions, a sentence has been given in Active/Passive voice. Out of the four-alternative suggested, select the one which best expresses the same sentence in Passive/Active voice.
He was seen leaving the room by them.

• 1
  They see him to leave the room
• 2
  They saw him leaving the room.
• 3
  They did see him leaving the room
• 4
  They have seen his leaving the room