Answer:
<h3>The answer is option B</h3>
Explanation:
The frequency of a wave can be found by using the formula

where
c is the velocity
From the question
wavelength = 0.39 m
c = 86 m/s
We have

We have the final answer as
<h3>200 Hz</h3>
Hope this helps you
How bright a star appears from Earth is the star's apparent magnitude.
The awnser is. 1728000 kilometers