Final answer:
Plots of paths in spacetime are typically drawn as curved lines by scholars of relativity, reflecting the curvature of spacetime due to the presence of mass.
Step-by-step explanation:
In the study of relativity, scholars typically represent plots of paths in spacetime as curved lines. According to Einstein's theory of relativity, light travels the shortest path in spacetime. However, when large concentrations of matter are present, they distort spacetime, causing the most direct paths to curve instead of being straight. This curvature of spacetime paths is evident in the world line of a particle, where a stationary particle has a world line that is a straight line parallel to the time axis, and a moving particle with constant velocity has a sloped line. In contrast, a particle that accelerates has a curved world line. Therefore, the correct answer would be (a) Curved lines.