If \[{{\left( \frac{\mathbf{m}}{\mathbf{n}} \right)}^{\mathbf{3/8}}}\mathbf{+}{{\left( \frac{\mathbf{n}}{\mathbf{m}} \right)}^{\mathbf{3/8}}}\mathbf{=9}\] then find the value of \[\,{{\left( \frac{\mathbf{m}}{\mathbf{n}} \right)}^{\mathbf{3/4}}}\mathbf{+}{{\left( \frac{\mathbf{n}}{\mathbf{m}} \right)}^{\mathbf{3/4}}}\].

• A. 79        
• B.  72
• C.  83
• D.  84
• E.  None of these