Which of the following equations defines the law of conservation of energy?

a. total energy = kinetic energy - potential energy
b. total energy = potential energy - kinetic energy
c. total energy = kinetic energy = potential energy
d. total energy = kinetic energy x potential energy

NONE of those choices defines the law of conservation of energy,
and none even describes it.  It's as if these choices belong to
a whole different question. 

In fact, none of the choices is even a true statement by itself !

A statement that defines the law of conservation of energy
would have to say something like this:

The total amount of energy in any closed system is constant.
The total amount of energy after any event or process is the
same as the total amount was before it.

Ithink the answer for this is: an electromagnet is a magnet  with a soft metal core.

  soil is  vegetal. in forest or prairies, as well as agricultural fields, dead plants are transformed by different kinds of living organisms.