The correct option is A 1 - (T4−T1)γ(T3−T2)
BC is an isobaric process and temperature from T2 to T3
Heat absorbed =Q1=Cp(T3−T2)
CD is an adiabatic process. So no heat is absorbed or rejected.
DA is an isochoric process.
So heat rejected =Q2=Cv(T4−T1) and AB is an adiabatic process. So, again, no heat is absorbed or rejected during AB.
Net amount of heat converted to work =Q2−Q1=Cp(T3−T2)−Cv(T4−T1)
So, efficiency η=Work doneHeat absorbed=Q2−Q1Q1=CP(T3−T2)−Cv(T4−T1)CP(T3−T2)
=1−CvCp.(T4−T1)T3−T2 =1−1γ.(T4−T1)T3−T2