What is occurring when two waves traveling along the same medium meet and cancel each other out?
a.) destructive interference
b.) constructive interference
c.) reflection
d.) refraction

Before answering this question, first we have to understand constructive and destructive interference.

Constructive interference occurs between two superimposing coherent waves when the crest of one wave falls on the crest of other wave or the trough of one wave on the trough of another wave.In this type of interference the net magnitude of resultant wave increases.

Here the superimposing waves are either in phase or they have a constant phase difference.

In case of destructive interference, the crest of one wave falls on the trough of another wave or vice versa. Destructive interference occurs when two superimposing waves are opposite in phase.If the amplitude of two waves are equal,then the the amplitude of resultant wave will be zero.

Here the phase difference between two waves is 180 degree.

Hence, the correct answer to the question will be a.) destructive interference

at positions a, g kinetic energy is maximum.

at position d, potential energy is maximum.