Select the option that expresses the given sentence in passive voice.
The postmaster had delayed the letter which was scheduled to arrive within four days.
1
The letter had delayed the postmaster which was scheduled to arrive within four days.
2
The letter was delayed by the postmaster which was scheduled to arrive within four days.
3
The postmaster had been delayed by the letter which was scheduled to arrive within four days.
4
The letter had been delayed by the postmaster which was scheduled to arrive within four days.