Final answer:
The National Coverage Determination (NCD) policy is the guideline that Medicare established to determine which diagnoses, signs, or symptoms are payable.
Step-by-step explanation:
The guideline that Medicare established to determine which diagnoses, signs, or symptoms are payable is known as the National Coverage Determination (NCD) policy. The NCD policy provides a framework for determining the medical necessity and appropriateness of services and interventions for specific conditions. It helps Medicare decide whether they will cover a particular medical procedure, service, or device based on evidence of effectiveness and cost-effectiveness.