What purpose do spring tabs serve in an aircraft?

Spring tabs are designed to aid the pilot in moving primary control surfaces, making option B the correct choice. These tabs help reduce the control forces required when manipulating flight controls, thereby enhancing the pilot's ability to operate the aircraft effectively, especially under varying conditions and speeds. By providing a mechanical advantage, spring tabs can assist in alleviating some of the aerodynamic loads on the control surfaces, allowing for smoother and more precise inputs.

The other options, while they might seem relevant in a broader context, do not accurately describe the specific function of spring tabs. For example, they do not directly contribute to flight safety measures, increase lift, or enhance navigational controls. Instead, their primary purpose revolves around facilitating the movement of primary control surfaces, making flying more manageable for the pilot.