Which of the following is a common defense for ships against air-to-surface weapons?

Surface-to-air missiles serve as a common and effective defense mechanism for ships against air-to-surface weapons. These missiles are designed to intercept and destroy incoming aerial threats before they can reach their target. By deploying surface-to-air missiles, ships can create a protective perimeter against hostile aircraft and missiles, drastically reducing the likelihood of a successful attack.

This capability allows naval forces to maintain operational effectiveness and security in contested environments, where potential aerial threats may emerge. Surface-to-air missile systems can be guided or unguided and are often integrated into the ship's combat system for automated target tracking and engagement, further enhancing the defensive layer.

The other options, while they may contribute to a ship's overall operational strategy or capability, do not provide the primary defense against aerial threats in the same direct manner. Enhanced speed can help evade threats but is not a dedicated defense system. High-explosive warheads are a type of munition rather than a defensive measure, and manned surface patrols, while useful for reconnaissance and situational awareness, do not inherently protect against air-to-surface threats like surface-to-air missiles do. In effect, surface-to-air missile systems are integral to a ship's ability to defend itself against air attacks.