The undefined notions of point, line, distance along a line, and distance around an arc serve as the foundational elements of geometry. They enable the construction and examination of various figures and shapes, which is crucial for developing geometric concepts. Among your response options, the most comprehensive and accurate choice is:
They are used as the building blocks of geometry and allow various figures and shapes to be constructed and examined.
This choice encapsulates the essential role these undefined notions play in the overall structure of geometry, providing a basis for further exploration and the development of geometric theories.