Solve the Equation by the Square Root Property $$( 7 x + 4 ) ^ { 2 } = 4$$

Multiple Choice

Solve the equation by the square root property.
- $$( 7 x + 4 ) ^ { 2 } = 4$$

A) $\left\{ - \frac { 2 } { 7 } , - \frac { 6 } { 7 } \right\}$
B) $\left\{ \frac { 0 } { 7 } \right\}$
C) $\left\{ - \frac { 2 } { 7 } , 0 \right\}$
D) $\left\{ \frac { 2 } { 7 } , \frac { 6 } { 7 } \right\}$