The Graph of the Equation Is a Circle $7 x^{2}+7 y^{2}=49$

Multiple Choice

The graph of the equation is a circle. Find the center and the radius, and then graph the circle.
- $7 x^{2}+7 y^{2}=49$

A) center $( 0,0 )$ ; radius $= 1$

B) center $( 7,7 )$ ; radius $= \sqrt { 7 }$

C) center $( 0,0 )$ ; radius $= 7$

D) center $( 0,0 )$ ; radius $= \sqrt { 7 }$