After putting stuff through google and some calculators, I’d say the answer is C.
Answer:
a)
degrees
b)
degrees
c)
degrees
Explanation:
If we have a vector
in a two dimensional space. The angle respect the x axis can be founded from the following expression:

And then the angle is given by:

Part a
Ax = 11 m and Ay = 11 m
For this case the angle would be:
degrees
Part b
Ax = 19 m and Ay = 11 m
For this case the angle would be:
degrees
Part c
Ax = 11 m and Ay = 19 m
For this case the angle would be:
degrees
False. A sound wave is an example of a mechanical wave, not an EM wave.
Hope this helps! :)