C. unbalanced is the correct answer for newton's first law.
energy never disappears, for example, if you give some kinetic energy to a ball and it stops few seconds later, friction steals this energy to ground which ball was going on. "Law of Conservation of Energy" tell us that energy can't disappear
Newtons first law of motion is also known as the law of inertia
Trust me, i'm a k12 student and its motor