Question

which pair of undefined terms is used to define a ray?
line and plane
plane and line segment
point and line segment
point and line

Explanation:

A ray is defined as a part of a line that starts at a single point (endpoint) and extends infinitely in one direction. The two undefined terms in geometry that form this definition are a point (the starting endpoint) and a line (the infinite path the ray follows from the point). The other options include terms that are not necessary for defining a ray.

Answer:

point and line