What defines a guided weapon?

A guided weapon is defined by its ability to have its trajectory controlled or modified after it has been launched or fired. This means that unlike unguided munitions, which follow a predetermined path based on their initial angle and speed, guided weapons can adjust their flight path in real-time to accurately strike a target.

This modification typically employs various technologies such as GPS, radar, or infrared guidance systems, which allow the weapon to correct its course mid-flight, ensuring higher precision and effectiveness in hitting moving or stationary targets.

The other options describe characteristics that do not specifically pertain to the definition of a guided weapon. For instance, being aimed before launch/firing applies to many types of weapons, guided or not, while referencing environmental constraints or close-range effectiveness does not relate to the defining attribute of guidance post-launch.