Pass a validated official test ?
Answer:
the first one is energy level
Explanation:
it would be at either A or B.
If it's a mechanical wave, then its speed depends on the physical characteristics of the medium.
If it's an electromagnetic wave, then its speed depends on the
electrical characteristics of the medium.
Either way, the properties of the medium determine the wave speed.
You want to change the speed ? You have to change the properties
of the medium.
The wavelength of the note is

. Since the speed of the wave is the speed of sound,

, the frequency of the note is

Then, we know that the frequency of a vibrating string is related to the tension T of the string and its length L by

where

is the linear mass density of our string.
Using the value of the tension, T=160 N, and the frequency we just found, we can calculate the length of the string, L: