Answer:
c.) sewage and industrial waste
Answer:
Frequency, 
Explanation:
Wavelength of a light wave is 450 nm. It is required to find the frequency of this light wave. The speed of light is given by c. So,

f is the frequency of this light

So, the frequency of this light is
.
The answer is C.
An object on the moon is six times lighter than on Earth.
Answer:
I think it would be A
Explanation:
Air, water, and warmth
Excuse my mistake if I get it wrong.