Answer is: D) time zones.
Earth is divided into 24 timezones.
Most timezones are exactly one hour apart.
Timezone is a region on Earth bounded by lines of longitude.
Coordinated Universal Time (UTC) is the basis for modern civil time.
For example, UTC±00:00 is the Western European Time (Ireland, Portugal and UK).
UTC+01:00 is Central European Time, West Africa Time.
