Help I don't understand this question:

Use the second law of thermodynamics to analyze the scientific and economic feasibility of each of the following processes:

AExtracting most mincerals dissolved in seawater.
BMining increasingly lower grade deposits of minerals
CUsing inexhaustible solar energy to mine minerals
DContinuing to mine, use, and recycle minerals at increasing rates

Verified Answer :

C) Using inexhaustible solar energy to mine minerals 

second law of thermodynamics deals with energy:
the branch of physical science that deals with the relations between heat and other forms of energy (such as mechanical, electrical, or chemical energy), and, by extension, of the relationships between all forms of energy.