What is a limitation of semi-active seekers?

The limitation of semi-active seekers that is identified as the correct answer is their requirement for an inorganic asset to paint the target. Semi-active seekers depend on external illumination of the target, typically provided by a radar or laser source on a platform such as an aircraft or a ground-based system. This means that the seeker cannot independently track targets; it relies on this additional support to provide the necessary information for guidance.

This reliance introduces a dependency on another platform's operational capabilities, which can pose a constraint if that asset is not available or if it becomes compromised. For instance, in a combat scenario, if the asset responsible for illuminating the target is taken out or unable to function effectively due to jamming or other countermeasures, the semi-active seeker may lose its ability to guide the weapon accurately to the target.

Other options present limitations associated with different types of seekers. While some may also face vulnerabilities, they do not specify the unique operational characteristic inherent to semi-active seekers that distinguishes their limitation regarding the necessity for an external targeting source.