Which certificate signifies that you can operate an aircraft?

The correct answer is the C of A, which stands for Certificate of Airworthiness. This certificate is crucial as it indicates that an aircraft meets safety standards and is fit for flight operations. It is issued by aviation authorities after thorough inspection and verification of the aircraft's conformity to design and safety regulations. This certification is essential for ensuring that the aircraft is maintained and operated in a safe condition.

The other options do not represent a certification that allows an individual to operate an aircraft. For example, a Certificate of Registration (C of R) indicates that the aircraft is officially registered but does not pertain to the operating capability. An Air Operator’s Certificate (AOC) is issued to an aircraft operator to certify that they can conduct commercial air transport operations, but it does not directly relate to an individual's ability to pilot an aircraft. The RTS, or Recurrent Training Schedule, is related to pilot training requirements but does not signify certification to operate an aircraft. Thus, the Certificate of Airworthiness is specifically about the aircraft's readiness for operation, making it the correct choice.