Final answer:
For a square one length below the shoulders haircut, the correct elevation is zero degrees or natural fall, ensuring an even square shape and blunt ends.
Step-by-step explanation:
In a square one length below the shoulders haircut, the correct elevation at which the hair is held for cutting is typically zero degrees or natural fall. This means that the hair should be combed down and cut at the same elevation as it grows from the head, which helps maintain an even length all around the haircut. Accurate elevation is crucial for achieving the desired square shape and ensuring that the ends of the hair are blunt and even.