Given:
The phenomenon of beats occurs when tuning two musical instruments
To find:
The reason
Step-by-step explanation:
Two waves with nearly the same frequencies and same amplitudes superimposed with each other produce beats. If an instrument is sounded against a standard frequency and tuned until the beats disappear then the instrument is in tune with the standard frequency. The tones interfere constructively and destructively with each other.
Hence, the second option is the correct one.