The radius of the circle passing through the foci of the ellipse $\frac{x^2}{16} +\frac{y^2}{9} = 1$ and having its centre at $(0, 3)$, is :

Question

( A ) $\sqrt{12}$ unit
( B ) $\frac{7}{2}$ unit
( C ) $4$ unit
( D ) $3$ unit