What is the celestial sphere?

A. The celestial sphere is a representation of how the entire sky looks as seen from Earth.
B. The celestial sphere is a model that shows the true locations in space of the Sun and a few thousand of the nearest stars.
C. The celestial sphere is a model of how the stars are arranged in the sky relative to our Sun, which is in the middle of the sphere.
D. It represents a belief in an Earth-centered universe, and hence is no longer considered to have any use.

Your answer is c. explanation: plasma  is the fourth state of matter, derived from the gaseous state of matter.  plasma  can contain free  electrons  and/or  ions. while  plasma is never neutral, it can either be positively or negatively charged.  gases, however, are electrically neutral.

stands for electromotive force and it is measured in volts. despite its name, it is not actually the force in the sense of being a "pushing" or "pulling" (not measured in newtons).an equation that relates emf,  ℰ,  to a battery's terminal voltage, v, current, i, and internal resistance, r, is    ℰ = v + irin this case, the emf can be interpreted as a voltage—a difference in electric potential.i would not say that it would be considered an energy. if emf can be defined as the energy/work per a unit charge from a battery or other electric source, then it is not strictly energy.