Which factor is listed as affecting body temperature?

• A. Time of day
• B. Eye color
• C. Shoe size
• D. Hair length

Answer: (A)

Body temperature naturally fluctuates over the course of a day because of the body's circadian rhythm. It tends to be cooler in the early morning and warmer in the late afternoon or evening. That time-of-day pattern is the factor that affects temperature readings. Eye color, shoe size, and hair length don’t influence how much heat the body produces or loses in a way that changes temperature measurements, so they aren’t considered factors affecting body temperature. This is why a temperature can vary within a normal range across the day, and why clinicians look at readings in context and may take multiple measurements if needed.