The combination of size of the base in relation to the diameter of the tool and the position of the tool in relation to the base is called:

The concept being described relates to how the size of the base interacts with the diameter of the tool and its positioning, which are crucial factors in hairstyling techniques. Base control refers specifically to how the size and placement of the base (the hair section near the scalp) influences the resulting volume and curl pattern from the tool used (like a curling iron or roller).

In hairstyling, proper base control is vital as it determines how close or far the tool is from the scalp. A smaller base size creates more volume and tighter curls, while a larger base allows for looser styles. Understanding base control allows a stylist to manipulate the hair texture and shape effectively, enhancing their styling results.

Other options may seem related but do not encapsulate this specific interplay. Tool positioning focuses more on the angle and manner in which the tool is held, while volume setting and diameter ratio are more about the outcomes rather than the foundational relationship between the base and tool diameter directly affecting the styling technique. Therefore, base control is the most accurate term to describe this relationship in hairstyling practices.