Final answer:
When it's 3 p.m. in the Central Time Zone, it's 2 p.m. in the Mountain Time Zone, due to the one-hour difference between these standardized time zones.
Step-by-step explanation:
The continental United States is divided into four main time zones: Eastern, Central, Mountain, and Pacific. When it is 3 p.m. Central Time, it is one hour earlier in the Mountain Time Zone, which means it would be 2 p.m. Mountain Time. The system of global standardized time zones helps individuals and travelers keep track of the local time as they move from one region to another, with most changes being a full-hour shift.