A Steam Engine Is Operating at Its Theoretical Maximum Efficiency $\degree$

A steam engine is operating at its theoretical maximum efficiency of 60%.If the waste heat has a temperature of 100 $\degree$ F (38 $\degree$ C) ,what is the temperature of the boiler?

A) 350 $\degree$ C
B) 94 $\degree$ C
C) 225 $\degree$ C
D) 504 $\degree$ C
E) 775 $\degree$ C