Add or Subtract $12 \sqrt [ 3 ] { 3 } + 3 \sqrt [ 3 ] { 3 }$

Multiple Choice

Add or subtract. Assume all variables represent positive real numbers.
- $12 \sqrt [ 3 ] { 3 } + 3 \sqrt [ 3 ] { 3 }$

A) $15 \sqrt [ 3 ] { 6 }$
B) $15 \sqrt [ 3 ] { 9 }$
C) $- 9 \sqrt [ 3 ] { 3 }$
D) $15 \sqrt [ 3 ] { 3 }$