If the endpoints of the diameter of a circle are (6, 3) and (2, 1), what is the standard form equation of the circle? A) (x + 4)2 + (y + 2)2 = 5 B) (x − 4)2 + (y − 2)2 = 5 C) (x + 4)2 + (y + 2)2 = 5 D) (x − 4)2 + (y − 2)2 = 5