Final answer:
The proper notation for AB is D) Line Segment AB if it specifies a fixed length between points A and B. A ray starts from a point and extends infinitely, while a line extends infinitely in both directions. Distance AB refers to the measure of length but is not a geometric figure.
Step-by-step explanation:
The proper notation for AB in geometry depends on the nature of the object being described. Given the choices presented, if AB represents a fixed length with two endpoints specifically at points A and B, then the correct notation would be D) Line Segment AB. A line segment is a part of a line that is bounded by two distinct end points and contains every point on the line between its endpoints.
In contrast, a ray is a portion of a line that starts at a point and extends infinitely in one direction, which would be Ray AB if point A is the starting point and the ray extends through B without ending. A line, denoted by Line AB, extends in both directions infinitely and has no end points. Distance AB could refer to the length or measure of either the line segment, the length of the path on a curve or arc in a geometric context, but it is not a type of geometric figure itself.