What is Greenwich Mean Time commonly referred to in military operations?

Greenwich Mean Time is commonly referred to as ZULU in military operations. This designation is part of a standardized method of communicating time using the NATO phonetic alphabet, where "Z" represents the Zulu time zone, corresponding to UTC (Coordinated Universal Time), which is essentially the same as GMT. Using ZULU eliminates confusion resulting from different time zones when coordinating military operations across various regions globally. This ensures operations can be synchronized without misunderstanding related to local time adjustments or daylight saving changes.

The other options do not accurately correspond to the military's terminology for Greenwich Mean Time. For example, while "Universal Standard Time" is a concept that relates closely to GMT/UTC, it is not the term employed in military contexts. Similarly, "Military Coordinated Time" does not reflect the established terminology used for operational timekeeping in military settings.