Answer:
The correct option is C
Explanation:
From the question we are told that
The initial speed of the rocket is
The speed of the rocket engine sound is
The final speed of the rocket is
The speed of the sound at would still remain V this because the speed of sound wave is constant and is not dependent on the speed of the observer(The mountain ) or the speed of the source (The rocket ).
A clear example when lightning strikes you will first see (that is because it travels at the speed of light which is greater than the speed of sound) but it would take some time before you hear the sound of the lightning
Here we see that the speed of the lightning(speed of sound) does not affect the speed of the sound it generates