When might a pilot need to verify the functionality of control cables?

Verifying the functionality of control cables is critical for maintaining the safety and operability of an aircraft's flight control system. Before takeoff, it is essential to ensure that all control surfaces respond correctly to pilot inputs, as any malfunction could lead to severe consequences once airborne. During engine run-up, where various systems are tested before flight, confirming the integrity of control cables is also important to ensure that the aircraft can be safely maneuvered during the engine operation. Additionally, after landing, checking for any signs of wear or damage to the control cables can help ensure they remain in good condition for future flights. Therefore, the need to verify control cable functionality applies at all these stages of flight operations, making the most comprehensive and prudent choice to be "all of the above."