The polytropic index (n) is given by

A. $$\frac{{\log \left( {{{\text{p}}_1}{{\text{p}}_2}} \right)}}{{\log \left( {{{\text{v}}_1}{{\text{v}}_2}} \right)}}$$

B. $$\frac{{\log \left( {\frac{{{{\text{p}}_2}}}{{{{\text{p}}_1}}}} \right)}}{{\log \left( {\frac{{{{\text{v}}_1}}}{{{{\text{v}}_2}}}} \right)}}$$

C. $$\frac{{\log \left( {\frac{{{{\text{v}}_1}}}{{{{\text{v}}_2}}}} \right)}}{{\log \left( {\frac{{{{\text{p}}_1}}}{{{{\text{p}}_2}}}} \right)}}$$

D. $$\log \left( {\frac{{{{\text{p}}_1}{{\text{v}}_1}}}{{{{\text{p}}_2}{{\text{v}}_2}}}} \right)$$

Answer: Option B