Amplitude, is the answer to the question
Answer:
water
is missing in above equation
hope it helps
Muttered is the same thing like mumble.
It's like when you are speaking and no one couldn't hear what you said.
So Muttered is when you say something low .
Hey there!
When light changes speed, it REFRACTS.
Your answer is going to be option C.
Hope this helps you.
Have a great day!