The correct description of the cycle of the air temperature in the office is:
At 7:00 a.m., the temperature begins gradually rising from 65 degrees to 80 degrees, where it stays until 7:00 p.m. Then, the temperature begins gradually dropping from 80 degrees to 65 degrees, where it stays until 7:00 a.m. the following day.
This choice accurately reflects the thermostat's behavior of changing the temperature settings at the specified times.