Find the Dimensions of a Rectangular Box of Maximum Volume $32,32,32$

Multiple Choice

Find the dimensions of a rectangular box of maximum volume such that the sum of the lengths of its 12 edges is 84 . Select the correct answer.

A) $32,32,32$
B) $32,7,16$
C) $7,7,7$
D) $7,84,7$
E) $4,8,16$