Which component protects the pins of the umbilical connector on the AGM-65 until just before loading?

The shielding cap serves a crucial purpose in protecting the pins of the umbilical connector on the AGM-65. Its design ensures that the pins remain secure and free from damage or contamination prior to loading. By covering the pins, the shielding cap prevents physical impacts and environmental exposure, which could otherwise lead to malfunctions. This protection is essential for maintaining the integrity of the electrical connections that are critical for the missile's performance.

While connector covers, protective sleeves, and sealing plugs serve their own functions in different contexts, they do not specifically fulfill the same role as the shielding cap in protecting the pins of the umbilical connector until the moment of deployment or loading. Thus, the shielding cap is specifically designed for this protective task, making it the correct answer in this scenario.