Two steam engines A and B have their sources at 600C and 400C and their sinks at 300C and 200C respectively

Q. Two steam engines A and B have their sources at 600C and 400C and their sinks at 300C and 200C respectively :

A.            They are equially efficient

B.            A is more efficient than B

C.            B is more efficient than A

D.            none of these

Answer: A is more efficient than B