a part of a line that has one endpoint and extends indefinitely in one direction
B
the set of all points in a plane that are a given distance away from a given point
C
lines that lie in the same plane and do not intersect
D
a part of a line that has two endpoints
Explanation
A ray starts at one endpoint and continues forever in one direction. Choice A gives this definition. Choice D describes a line segment, which has two endpoints.
AI-written and checked against the verified answer.