A and B are two points on a co-ordinate plane. All the points, in the same plane as A and B, whose distance from B is twice that from A lie on

1) a straight line intersecting AB at a point O such that 2AO = BO.
2) a circle with center at a point O on AB such that AO = 2BO.
3) a circle with center at a point O on AB extended such that 4AO = BO.
4) None of these.