Final answer:
Body mass index is not considered a vital sign; rather, vital signs include body temperature, heart rate, respiration rate, and blood pressure.
Step-by-step explanation:
Among the options provided, Body mass index (BMI) is NOT considered one of the vital signs. Vital signs serve as critical indicators of a person's health and include body temperature, which is normally around 37 °C or 98.6 °F, heart rate with a usual range of 60-100 beats per minute, respiration rate, typically 12-18 breaths per minute, and blood pressure, which should be between 90/60 and 120/80 mm Hg. Alterations in any of these vital signs can be a sign of disease. BMI, on the other hand, is a measure of body fat based on height and weight, used to categorize individuals into various weight ranges, and while it's important for overall health assessment, it's not a vital sign that is measured in acute medical settings.