How do transmittance, absorbance, and molar absorptivity differ? Which one is proportional to concentration?

The transmittance is the amount of energy that a body goes through in a certain amount of time without being absorbed and the absorbance is the amount of light that is absorbed by a solution.

There is no difference between absorptivity and molar absorptivity because the two terms express the same idea, because molar absorptivity is the absorbance of a solution per unit path length and concentration, so that the absorbance is proportional to concentration.