If the Black Hole in the Center of the Galaxy

If the black hole in the center of the Galaxy is 4 * 10⁶ solar masses, what would be its radius (that is, the radius of its event horizon) ?

A) 1.2 * 10⁷ m (about twice the radius of Earth)
B) 1.2 * 10⁹ m (about twice the radius of the Sun)
C) 1.2 * 10¹⁰ m (about one-fifth of Mercury's orbital radius)
D) 1.2 * 10¹² m (almost twice Jupiter's orbital radius)