Solve the Equation $$x ^ { 2 } = 9$$ A) $\pm \mathrm { i } \sqrt { 3 }$

Solve the equation.
- $$x ^ { 2 } = 9$$

A) $\pm \mathrm { i } \sqrt { 3 }$
B) $\pm \sqrt { 3 }$
C) $\pm 3 \mathrm { i }$
D) $\pm 3$