Solve the Quadratic Inequality $$x ^ { 2 } - 3 x - 18 \leq 0$$

Multiple Choice

Solve the quadratic inequality. Write the solution set in interval notation.
- $$x ^ { 2 } - 3 x - 18 \leq 0$$

A) $( - \infty , - 3 ]$
B) $[ 6 , \infty )$
C) $[ - 3,6 ]$
D) $( - \infty , - 3 ] \cup [ 6 , \infty )$