Factor Out the Greatest Common Factor $$5 x ^ { 3 } + 20 x$$

Multiple Choice

Factor out the greatest common factor. Simplify the factors, if possible.
- $$5 x ^ { 3 } + 20 x$$

A) $5 x ^ { 2 } ( x + 4 )$
B) $5 x \left( x ^ { 2 } + 4 \right)$
C) $5 x \left( x ^ { 2 } + 4 x \right)$
D) $5 x \left( x ^ { 2 } + 15 x \right)$