Answer:
B.) by interfering with sound waves
Explanation:
As we know that the interference of sound waves is of two types
1). constructive interference
2). destructive interference
now we know that constructive interference means the resultant intensity will be more than the intensity of interfering waves as here two waves are in same phase.
In destructive interference the resultant of two waves is given by the minimum resultant of the intensity as here the phase of two waves are opposite to each other.
So we will say that

here in case of noise cancelling headphones we know that the phase of noise is always made in opposite phase with the sound which is used to cancelled the noise.
This will reduce the noise and we will get a clear sound
Answer: b is sedimentary. c is metamorphic. and a is igneous.
Explanation:
Sound waves in air (and any fluid medium) are longitudinal waves because particles of the medium through which the sound is transported vibrate parallel to the direction that the sound wave moves.
Answer:
x component 60.85 m
y component 101.031 m
Explanation:
We have given distance r = 118 km
Angle which makes from ground = 58.9°
(a) X component of distance is given by 
(b) Y component of distance is given by 
These are the x and y component of position vector