Perform the Operations and Simplify $$\left( 8 x ^ { 3 } - 3 x ^ { 2 } \right) + \left( 5 x ^ { 3 } - 3 x \right)$$

Multiple Choice

Perform the operations and simplify. $$\left( 8 x ^ { 3 } - 3 x ^ { 2 } \right) + \left( 5 x ^ { 3 } - 3 x \right)$$

A) $\quad 13 x - 3 x ^ { 2 } - 3 x ^ { 3 }$
B) 0
C) $\quad 7 x ^ { 3 }$
D) $\quad 13 x ^ { 3 } - 3 x ^ { 2 } - 3 x$