Find the Product A) $- 10 - 10 \sqrt { 3 } i$

Multiple Choice

Find the product. Write the product in rectangular form, using exact values.
- $\left[ 4 \left( \cos 120 ^ { \circ } + \mathrm { i } \sin 120 ^ { \circ } \right) \right] \left[ 5 \left( \cos 120 ^ { \circ } + \mathrm { i } \sin 120 ^ { \circ } \right) \right]$

A) $- 10 - 10 \sqrt { 3 } i$
B) $10 \sqrt { 3 } - 10 \mathrm { i }$
C) $- 10 \sqrt { 3 } + 10 \mathrm { i }$
D) $10 + 10 \sqrt { 3 } \mathrm { i }$