Final answer:
A ray is defined as starting at a point and extending infinitely in one direction along a line, so the correct answer is D) point and line.
Step-by-step explanation:
The question asks which pair of underlined terms is used to define a ray. Let's first clarify what each of the geometrical terms means:
- A point indicates an exact location in space and has no size, area, length, or any other dimension.
- A line is a straight one-dimensional figure that has no thickness and extends infinitely in both directions.
- A line segment is a part of a line that is bounded by two distinct end points.
- A plane is a flat, two-dimensional surface that extends infinitely in all directions.
A ray is defined by two of these terms: it starts at one point (called the endpoint) and extends infinitely in one direction along a line. Therefore, the correct answer is D) point and line.