Simplify by Combining Like Radicals $\sqrt [ 3 ] { 189 x } + \sqrt [ 3 ] { 7 x }$

Multiple Choice

Simplify by combining like radicals. The variable represents a positive real number. $\sqrt [ 3 ] { 189 x } + \sqrt [ 3 ] { 7 x }$

A) $4 x \sqrt [ 3 ] { 7 }$
B) $4 \sqrt [ 3 ] { 7 x }$
C) $\sqrt [ 3 ] { 10 x }$
D) $4 + \sqrt [ 3 ] { 7 x }$
E) $\sqrt [ 3 ] { 7 x }$