The pressure ratio known as critical pressure ratio for maximum discharge through the nozzle is given by:

• A. \(\frac{{{p_2}}}{{{p_1}}} = {\left( {\frac{{n + 1}}{2}} \right)^{n/n - 1}}\)
• B. \(\frac{{{p_2}}}{{{p_1}}} = {\left( {\frac{2}{{n + 1}}} \right)^{n - 1/n}}\;\)
• C. \(\frac{{{p_2}}}{{{p_1}}} = {\left( {\frac{2}{{n + 1}}} \right)^{n/n - 1}}\)
• D. \(\frac{{{p_2}}}{{{p_1}}} = {\left( {\frac{{n + 1}}{2}} \right)^{n - 1/n}}\)