On a scale used to grade heart murmurs from 1 to 6, which end of the scale represents the most severe murmur?

1. A murmur describes an unusual heart sound caused by turbulent blood flow. 2. Murmurs are graded on a scale of 1 to 6. 3. Grade 1 is the most common and least serious, while the most severe grade on this scale is 6. 4. Grade 3 is only a mid-range value, and the scale does have a defined most-severe endpoint, so none of the other options is correct. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 19 "The Cardiovascular System: The Heart", section 19.3, p. 864_