A Carnot engine, whose efficiency is 40%, takes in heat from a source maintained at a temperature of 500 K. It is desired to have an engine of efficiency 60%. Then, the intake temperature for the same exhaust (sink) temperature must be

Question

( A ) 600 K
( B ) efficiency of Carnot engine canno be made larger than 50%
( C ) 1200 K
( D ) 750 K