c
(c)\(\frac{{{I_{\max }}}}{{{I_{\min }}}} = {\left( {\frac{{\sqrt {\frac{{{I_1}}}{{{I_2}}}} + 1}}{{\sqrt {\frac{{{I_1}}}{{{I_2}}}} - 1}}} \right)^2} = \left( {\frac{{\sqrt {\frac{9}{1}} + 1}}{{\sqrt {\frac{9}{1}} - 1}}} \right) = \frac{4}{1}\)