Final answer:
The correct conversion of 9:00 p.m. to military time is 2100 hours (option B).
Step-by-step explanation:
The correct conversion of 9:00 p.m. to military time is 2100 hours (option B).
In military time, the hour runs from 00 to 23. To convert 9:00 p.m., we subtract 12 from the hour since p.m. starts counting from 12. This gives us 9 - 12 = 21. Therefore, 9:00 p.m. is equivalent to 2100 hours in military time.