Long time ago, people saw the constellations as patterns in the sky. They names these patterns and tell stories about them. What people saw laong time ago are just mere patterns which forms animals and shapes. We got the names of our constellations from the Greeks who named the constellations after the mythological heroes and mythological legends.
Air caught in the ball of foil makes the ball less dense than water
Answer:

Explanation:
Given that,
Wavelength, 
We need to find the frequency of the violet light.
We know that the relation between frequency and wavelength is given by :

So, the frequency of violet light is
.
Answers A and C can be automatically eliminated because evaporation has to do with the water cycle and magnetism has to do with electric current and such. Next we can eliminate B or distillation because it also has to do with water/liquids. Therefore, the answer is D or filtration because it is the only answer left.
I hope this helps!