Question

I THINK I KNOW THE ANSWER BUT I NEED VERIFICATION!!!!!!!

Answer 1

Yes, the answer is in fact C. All of the above.

Variable stars are stars that change in brightness. The change could be due to the physical change in the star or it could also be caused when another star crosses another, or in other words eclipse. 

Answer 2

The answer is All of the above.  Variable Stars include White Dwarf Stars, Red Giant Stars & Binary Stars.   A white dwarf is what stars like the Sun become after they have exhausted their nuclear fuel. A red giant star is a dying star in the last stages of stellar evolution.  Binary stars are two stars  orbiting a common center of mass. The brighter star is officially classified as the primary star, while the dimmer of the two is the secondary .