A circle of non-zero radius has origin as its centre. If it passes through the point of intersection of two curves $$y^2 = 4ax$$ and $$x^2 = 4ay$$, then its equation is

A

$$x^2 + y^2 = 16a^2$$

B

$$x^2 + y^2 = a^2$$

C

$$x^2 + y^2 = 4a^2$$

D

$$x^2 + y^2 = 32a^2$$