The correct option is D 01:00 AM
We know that, the time from mid night to mid day is denoted by AM (Ante Meridiem).
Similarly, the time from mid day to mid night is denoted by PM (Post Meridiem).
1'o'clock at night will be a time between mid night and mid day.
Hence, it will be denoted by AM.
So, 1'o'clock at night is denoted by 01:00 AM.