Anton, Bertha, and Cecilia All Consume Crackers and Music

Anton, Bertha, and Cecilia all consume crackers and music.Crackers are a pure private good and music is a pure public good.Their utility functions are U A (c A, m) = c A m, U B (c B, m) = c B m, and U B (c C, m) = 2c C m, where c A is Antons cracker consumption, c B is Berthas cracker consumption, c C is Cecilias cracker consumption, and where m is the amount of music jointly consumed by all three of them.Music is measured in hours.Crackers cost $1 each.Music costs $10 an hour.Antons wealth is $30, Berthas wealth is $50, and Cecilias wealth is $20.What is the efficient amount of music for them to consume?

A) 2 hours
B) 3 hours
C) 4 hours
D) 5 hours
E) 6 hours