Question

Which figure represents an undefined term?

A line extends right and up from point X through point Y with an arrow instead of an endpoint.
A line connects point X and point Y.
A line extends right and up from point X through point Y with an arrow instead of an endpoint. A line extends right and down from point X through point W with an arrow instead of an endpoint.
A line extends both directs between point X and point Y.

Answer 1

The fourth figure — the line with arrows on both ends through X and Y. That figure represents a line, which (along with point and plane) is an undefined term in geometry.