Find the Equation of the Circle Graphed Below $\quad x ^ { 2 } + y ^ { 2 } = 1$

Multiple Choice

Find the equation of the circle graphed below.

A) $\quad x ^ { 2 } + y ^ { 2 } = 1$
B) $\quad x ^ { 2 } + y ^ { 2 } = 25$
C) $x ^ { 2 } + y ^ { 2 } = 5$
D) $x ^ { 2 } + y = 25$
E) $y ^ { 2 } = x ^ { 2 } + 25$