Everything we know about stars comes from studying their mass color temperature radiation/light age

Everything we know about stars comes from studying their radiation/light. By measuring the wavelength or frequency of light coming from objects in the universe, we can learn something about their nature.  Starts emit a range of wavelengths. The frequency of light is directly related to its color, so it follows that stars have different colors because they have different peak wavelengths of light.

since you're a real machine, your ama is always less than your ima, because you can never totally eliminate friction.

your answer is c! hope this : )