Which component inside the guidance window of the AGM-65 must be checked before loading?

The correct choice emphasizes the need to check the humidity indicator inside the guidance window of the AGM-65 before loading. The humidity indicator is crucial because excessive moisture can adversely affect the guidance system's performance and reliability. This component provides a visual indication of the humidity level, allowing personnel to ensure that conditions are within acceptable parameters for safe operation and effectiveness of the munition. Maintaining proper humidity levels is essential for the reliability of the electronic components within the guidance system, as high humidity can lead to corrosion or malfunction of sensitive parts.

The importance of other components, such as the pressure gauge, optical sensor, and temperature sensor, while relevant in different contexts, does not take precedence over the humidity indicator for this specific process. Each of these may have their own significance in terms of operational readiness, but checking the humidity indicator is a critical step to help guarantee that the AGM-65 can function correctly once deployed.