After Taking the Patient's Temperature,the Nurse Documents the Value and the Route

After taking the patient's temperature,the nurse documents the value and the route used to obtain the reading.Why is this done?

A) Temperatures are the same regardless of the route used.
B) Temperatures vary depending on the route used.
C) Temperatures are cooler when taken rectally than when taken orally.
D) Axillary temperatures are higher than oral temperatures.