Cho \({\sin ^6}x + {\cos ^6}x = \frac{{4 - 3{m^2}}}{4}\) (là hằng số cho trước).

A. \(\frac{{{{\left( {2 - {m^2}} \right)}^2}}}{4} - \frac{{{m^4}}}{8}\)

B. \(\frac{{{{\left( {2 - {m^2}} \right)}^2}}}{4} - \frac{{{m^4}}}{4}\)

C. \(\frac{{{{\left( {2 - {m^2}} \right)}^2}}}{4} + \frac{{{m^4}}}{8}\)

D. \(\frac{{{{\left( {2 - {m^2}} \right)}^2}}}{4} - \frac{{{m^2}}}{{16}}\)