The correct option is D P.M (post meridiem)
In a day there are 24 hours but in analog clock only 12 hours are there thatswhy same time appears two times in a day one before midday and one after midday.
Therefore, to make the difference between before midday and after midday time, we use the terms A.M (ante meridiem) and P.M (post meridiem) respectively.
For example: 6:30 before midday is denoted by 6:30 A.M. and 6:30 after midday is denoted by 6:30 P.M.