Answer: The correct answer is wave front.
Step-by-step explanation:
Wave front: It is a locus of the points. These points are characterized by the propagation of positions. The wave front is represented as surface of identical phase. It is perpendicular to the direction of propagation.
The simplest form of wave front is the plane wave. Here, the rays are parallel to another.
Therefore, a wave front is a line in which waves that are moving together are all in the same phase.