Answer:
Sewage is a liquid containing wastes from households, industrial and agricultural activities discharged into water and it is dirty water.
Second law of thermodynamics states entropy of the universe is always increasing. entropy always increases in a spontaneous process .
option B) second law of thermodynamics
for example if we keep a hot cup of coffee the heat is lost to surrounding and entropy( randomness increases) since it is a natural process entropy of universe increases.