Answer:
Wave X has a shorter wavelength.
Explanation:
It is given that, two sound waves (wave X and wave Y) are moving through a medium at the same speed.
Speed of a wave is given by :

Where,
is frequency
is wavelength
The relation between the frequency and the wavelength is inverse. Wave X has greater frequency than Y, then wave X has a shorter wavelength.
Hence, the correct option is (B) "has a shorter wavelength".
If there are two equal and opposite forces on the SAME THING, then the thing doesn't accelerate. You're right about that. But the action and reaction forces act on two different things. The bullet and the rifle. The ball and the bat. The airplane and the air. etc. So BOTH can accelerate.
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