The efficiency of a gas turbine is given by

• A. <img src="/_files/images/mechanical-engineering/thermodynamics/253-233-1.png">
• B. <img src="/_files/images/mechanical-engineering/thermodynamics/253-233-2.png">
• C. <img src="/_files/images/mechanical-engineering/thermodynamics/253-233-3.png">
• D. <img src="/_files/images/mechanical-engineering/thermodynamics/253-233-4.png">