Let $f ( x , y , z ) = x y z$

Multiple Choice

Let $f ( x , y , z ) = x y z$ with constraint $2 x y + 3 x z + y z = 72$ . Then f has a relative maximum at

A) $( - 2 , - 6 , - 4 )$
B) $( 2 , - 6 , - 4 )$
C) $( - 2 , - 6,4 )$
D) $( 2,6,4 )$
E) $( - 2,6 , - 4 )$