[Cecil4]

Is the real answer "none of the above", even though B is poor wording.

R1 is on second base and R2 is on first base. R1 gets caught in a rundown between second and third. As R1 retreats to second, F4 blocks the bag, prior to receiving the ball, obstructing R1 from sliding into the bag. F6 then tags R1. The correct call is:
A. The umpire initially signals a delayed dead ball and when R1 is put out between the two bases where she was obstructed the ball becomes dead. R1 is awarded third and R2 will be awarded second as in the umpire's judgement each would have been reached safely had there been no obstruction by F4.
B. The umpire signals a dead ball and R1 and R2 return back to their initial bases prior to the play.
C. The ball is live. R1 will be awarded third due to obstruction by F4 and R2 remains on first because R2 was not involved in the rundown.
D. The umpire signals a delayed dead ball. R1 and R2 are not called out and both runners return to their initial bases while F4 is ejected.