Final answer:
The projection angle for medium graduation is B) 45 degrees, a moderate transition length in haircutting that determines shape and weight distribution.
Step-by-step explanation:
The correct projection angle used to create medium graduation is B) 45 degrees. Medium graduation refers to the degree of length change in a haircut; with a graduation at 45 degrees, there is a noticeable but moderate transition in the lengths of the hair.
The concept of projection angles is crucial in styling and cutting hair, as it helps determine the shape and weight distribution throughout the hairstyle. Similar principles can be seen in physics, where angles play a significant role in projectile motion and vector analysis.