If R1 misses touching second base while advancing to third, what is the outcome?

When R1 misses touching second base while advancing to third, the most appropriate outcome is that R1 is out if the defensive team makes a valid appeal. This situation applies the rule concerning base running and the responsibilities of the runner to ensure that all bases are touched in the proper order.

The momentum of R1’s run does not negate the rule that requires touching all bases. If the defense is aware of R1's failure to touch second base and they successfully appeal during the game, R1 will be ruled out. Therefore, while B1 is allowed to remain on first base as a separate entity in this play, the key point is that R1, having failed to correctly touch second base, can be called out.

The other outcomes do not align with the established rules of base running when an appeal is made regarding a missed base. R1 cannot be safe at home without fulfilling the obligation of touching all bases, nor can R1 appeal to touch second base after scoring because an appeal must be made before the run is counted. Additionally, R1 is not automatically granted third base because missing a base does not provide any advantage. Thus, A correctly captures the ruling in this scenario.