Final answer:
The statement is true (a); body temperature is generally the lowest between 4 am to 6 am due to the body's circadian rhythm and thermoregulation process.
Step-by-step explanation:
The statement that body temperature is the lowest between 4 am to 6 am is true. Our body temperature follows a circadian rhythm, rising throughout the waking day and peaking in the afternoon.
It decreases during sleep, with the lowest point typically occurring during the early morning hours, which can be from 4 am to 6 am. This phenomenon is part of the body's thermoregulation process, a form of negative feedback where the body can maintain its core temperature within a set range, roughly around 36.5-37.5 °C (97.7-99.5 °F), even when external temperatures vary considerably.