Which aircraft component is primarily responsible for low observable performance?

The outer mold line is primarily responsible for low observable performance because it shapes the aircraft's structure in a way that contributes to reducing its radar cross-section and overall detectability. This refers to the external contours and surfaces of the aircraft, which are designed to scatter radar waves rather than reflecting them directly back to the source. The concept of shaping, along with the use of specialized materials, is integral to achieving low observable characteristics that are crucial for stealth operations.

In contrast, while the engine design can influence signatures, it is typically the exterior shape and surface treatments that have a more dominant impact on low observability. The cockpit controls and landing gear have little to no effect on the aircraft's radar signature and are not optimized for stealth. Their roles are focused more on functionality and pilot operation rather than minimizing detectability. Therefore, the outer mold line stands out as the key factor in determining an aircraft's low observable performance.