The graph below plots four main sequence stars according to their luminosity and temperature.

There is a positive correlation between luminosity and mass of stars, meaning the more luminous a star is, the more massive it is likely to be as well. Given this, the masses of the stars should be in descending order of brightness. 

Star 1 is the most luminous, so it should be heaviest, and the luminosity descends to Star 4.
Option B is the only chart that conforms to this, so it is the answer. 

Answer is B