Superposition of two waves having the "same frequency", "same amplitude", and "travelling" in the same direction is called:

Explanation

OPTION A: When two waves having the same frequency, amplitude, and a constant phase relationship are propagating through a certain region of space in the same direction. They reinforce each other at some points while canceling the effect of each other at other points. This phenomenon of the superposition of waves is called interference. OPTION B: The spreading of light waves around the edges of a narrow opening is called diffraction. OPTION C: The periodic motion in the loudness of sound which is heard when two notes of nearly the same frequency are played simultaneously, is called beats.OPTION D: When two plane waves having the same amplitude and frequency, traveling with the same speed in opposite directions along a line, are superposed, a wave obtained is called a stationary or standing wave.