What happens if R1 does not retouch first base after a fly ball?

When a runner does not retouch the base after a fly ball is caught, it results in a situation that can be appealed by the defensive team. If the defensive team observes that the runner has not properly retouched the base before advancing, they are allowed to make an appeal play at first base. In this scenario, the correct outcome is that the runner is called out on appeal. This reinforces the importance of base running rules and the necessity for runners to adhere to the proper protocols after a caught ball to avoid being put out. The other choices do not reflect the consequences of failing to retouch the base after a catch, as the runner must always maintain compliance with the rules governing base running to avoid being called out.