I think it is B Because it sounds like the best choice
Answer:

Explanation:
By Snell's law we know at the left surface




now we have


now on the other surface we know that
angle of incidence = 

so again we have

so we have


also we know that


By solving above equation we have

answer
option d is the correct answer
explanation
as we know frequency is equal to 1 /t
f= 457 Hz
t=1
SO, 1/457
=0.0022sev
Explanation:
<h3>1.) Regeneration is the natural process of replacing or restoring damaged or missing cells, tissues, organs, and even entire body parts to full function in plants and animals.</h3>
2.) When noise is added to analogue signals, it usually sounds like background hiss. Such noise can not be removed so the original clean signal can not be re-created or re-generated.