The polytropic index (n) is given by

• A. <img src="/_files/images/mechanical-engineering/thermodynamics/244-126-1.png">
• B. <img src="/_files/images/mechanical-engineering/thermodynamics/244-126-2.png">
• C. <img src="/_files/images/mechanical-engineering/thermodynamics/244-126-3.png">
• D. <img src="/_files/images/mechanical-engineering/thermodynamics/244-126-4.png">