The equation of a circle with origin as centre and passing through the vertices of an equilateral triangle whose median is of length `3a` is

Options

A. `x^(2)+y^(2)=9a^(2)`
B. `x^(2)+y^(2)=16a^(2)`
C. `x^(2)+y^(2)=4a^(2)`
D. `x^(2)+y^(2)=a^(2)`

Answer

C