Answer:
c. Groundwater contamination at a fracking site
Explanation:
all others could be sources from tens of square kilometers of surface area.
Fracking is limited to within a short range of the well hole.
I believe the last one about the bike is correct.
Answer:
15.32°
Explanation:
We have given the wavelength 
Diffraction grating is 1460 lines per cm
So
(as 1 m=100 cm )
For maximum diffraction
here m is order of diffraction
So 


Rotation. The Earth rotates around the sun on it’s axis. Depending how far north or south you live, and the angle of the sun at different times of year gives you the amount of daylight or darkness you will receive. So the length of day or night depends on how much the sun is able to reach the spot on a round object such as the planet Earth.