Answer:
A. Through a given point not on a given line, there is exactly one line parallel to the given line.
Explanation:
The fifth postulate of Euclidean geometry is often referred to as the Parallel Postulate.
A. Through a given point not on a given line, there is exactly one line parallel to the given line. This statement is actually the Parallel Postulate, so it is the correct answer.
B. All right angles are equal to one another. This statement is actually the Fourth Postulate, also known as the Right Angle Postulate.
C. Any straight line segment can be extended indefinitely. This statement is the Second Postulate, also known as the Line Extension Postulate.
D. A circle can be drawn with any center and radius. This statement is the Third Postulate, also known as the Circle Postulate.
Therefore, the correct answer is:
A. Through a given point not on a given line, there is exactly one line parallel to the given line.