Illegally Batted Ball on Suicide Squeeze

 
With no outs and a runner on third base (R3), the defense suspects a suicide squeeze has been called. With the pitcher in the set position, R3 breaks for home.
 
The pitcher legally steps back off the rubber with his pivot foot and throws home. B1 bunts the ball, R3 scores, and B1 is retired at first base.
 
What should the umpire do now?
A) Legal play, so "play on". R3 scores and B1 is out.
B) The pitcher balked, so R3 is awarded home and B1 remains at bat.
C) B1 is called out for interfering with the play at the plate.
D) R3 is called out because of B1's actions.
E) Both C and D (B1 and R3 are declared out).
 
Call
In the situation below, the pitcher properly stepped off the pitching rubber... so the pitcher did not throw a pitch -- rather, he was making a throw to home to attempt to retire R3. B1 is no longer allowed to hit the throw home. If B1 does, then he has interfered. Since the runner was attempting to steal home, and B1 interfered, then R3 is out. B1 remains at the plate (answer "D").