Find the Radius of the Sphere Whose Equation Is $x ^ { 2 } + 2 x + y ^ { 2 } + z ^ { 2 } = 4$

Multiple Choice

Find the radius of the sphere whose equation is $x ^ { 2 } + 2 x + y ^ { 2 } + z ^ { 2 } = 4$ .

A) 1
B) $\sqrt { 2 }$
C) $\sqrt { 3 }$
D) 2
E) $\sqrt { 5 }$
F) $\sqrt { 6 }$
G) $\sqrt { 7 }$
H) $2 \sqrt { 2 }$