There are two items to remember with questions about time:

1. Time is given using UTC and the 24 hour clock.
2. Time is always given in minutes only unless there is any possibility of confusion. This question does not indicate that this is the case here, so just minutes is the correct answer.

Looking at the answer options:

Five seven UTC → INCORRECT. There is no need to say ‘UTC’.

Five seven → CORRECT. No mention is made in the question about possible confusion, so the hour has not been included.

Twenty three fifty seven → INCORRECT. ‘Fifty seven’ is incorrect phraseology. Each digit should be pronounced separately.

Two three five seven UTC. → INCORRECT. There is no need to say ‘UTC’.

ICAO Annex 10 — Aeronautical Telecommunications
Chapter 5

5.2.1.4.1.8. PANS- When transmitting time, only the minutes of the hour should normally be required. Each digit should be pronounced separately. However, the hour should be included when any possibility of confusion is likely to result.
Note: The following examples illustrate the application of this procedure (see 5.2.1.4.3.1 for pronunciation).