Answer:
C. energy can neither be created nor destroyed
Explanation:
The law of conservation of mass states that in a chemical reaction mass can neither be created nor destroyed. Similarly, the law of conservation of energy states that the amount of energy in an isolated system is conserved ie. the amount of energy can neither be created nor destroyed, but instead changes form.
Natural Selection, unless you were born in a lab which would be unnatural/artificial, and not too likely with today's technology. (Maybe one day.)
If you use more than one independent variable at a time, and will observe a change, you will not know which variable contributed to a changed result.
