Equation of a circle in standard form with center (h,k) and radius r is given by :
[tex] (x-h)^{2} +(y-k)^{2} =r^{2} [/tex]
In the given question the center of circle is lying on y axis so h=0 .Radius r=3 Substituting these values in the equation of circle we have:
[tex] (x-0)^2+(y-k)^2=3^2 [/tex]
Expanding we have :
[tex] x^2+y^2-2yk+h^2=9 [/tex]
Subtracting 9 both sides
[tex] x^2+y^2-2yk+h^2-9=0 [/tex]
Comparing this with the equation of circle in general form
A=1,B=1,C=0
If D=-8 then E=7
So option C is the right answer
