If $m ( x ) = x ^ { 3 }$

Multiple Choice

If $m ( x ) = x ^ { 3 }$ and $n ( x ) = \sqrt { 6 + x }$ find the function value, if possible. $( m - n ) ( - 5 )$

A) $- 126$
B) 124
C) $- 124$
D) Not a real number