Use a Vertical Format to Add the Polynomials $$\begin{array} { l } 3 x ^ { 7 } + 6 x ^ { 6 } - 5 x \\2 x ^ { 7 } + 3 x ^ { 6 } - 4 x \\\hline\end{array}$$

Multiple Choice

Use a vertical format to add the polynomials.
- $$\begin{array} { l } 3 x ^ { 7 } + 6 x ^ { 6 } - 5 x \\2 x ^ { 7 } + 3 x ^ { 6 } - 4 x \\\hline\end{array}$$

A) $5 x ^ { 7 } + 9 x ^ { 6 } - 9 x$
B) $5 \times ^ { 14 }$
C) $- 3 x ^ { 7 } + 6 x ^ { 6 } + 2 x$
D) $5 x + 9 x ^ { 7 } - 9 x ^ { 6 }$