2400 hour time starts at which time?

The 2400 hour time, also known as military time, starts at 0000. This represents midnight at the start of a new day. In the 24-hour clock system, the day begins at this point, progressing through the day until it resets at 2400, which is equivalent to 0000 of the following day. This system eliminates the ambiguity between AM and PM times that is present in the 12-hour clock format. Therefore, 0000 effectively signifies the start of the day, making it the correct answer.