Find the Equation of the Circle Graphed Below $y ^ { 2 } = x ^ { 2 } + 4$

Multiple Choice

Find the equation of the circle graphed below.

A) $y ^ { 2 } = x ^ { 2 } + 4$
B) $\quad x ^ { 2 } + y ^ { 2 } = 2$
C) $x ^ { 2 } + y ^ { 2 } = 4$
D) $\quad x ^ { 2 } + y = 4$
E) $\quad x ^ { 2 } + y ^ { 2 } = 1$