The given value is,
[tex]\sqrt[]{-24}[/tex]We can write this as,
[tex]\sqrt[]{-24}=\sqrt[]{24\times-1}[/tex]As we know, 24 = 4 x 6 and,
[tex]\sqrt[]{-1}=i[/tex]the above expression can again be rewritten as,
[tex]\sqrt[]{-24\times-1}=\sqrt[]{4\times6}\times i=2i\sqrt[]{6}[/tex]Thus, the last option is correct.