What should be confirmed visually regarding slats and ice?

The correct choice is that slats should be confirmed visually to be free of ice. Ice accumulation on slats can significantly impact the aerodynamic efficiency of the aircraft, particularly during low-speed segments of flight such as takeoff and landing. When slats are iced up, they cannot perform their function of enhancing the lift provided by the wing, which can lead to increased stall speeds or loss of control.

Therefore, ensuring that slats are free of ice is critical for maintaining safety and performance standards during flight operations. Conducting a visual inspection allows the flight crew to ascertain that the flight control surfaces, including slats, are functioning as designed and that the aircraft is safe for operation. This visual confirmation is a crucial part of pre-flight checks, especially in winter weather conditions where ice formation is a concern.

While the other options may pertain to issues that can arise with slats, they do not address the immediate need to ensure that they are clear of ice prior to flight, which is essential for safe takeoff and performance.