What is a key feature of the RGM-84 Harpoon missile?

The RGM-84 Harpoon missile is specifically designed for shipboard launch against surface targets, making this option the correct answer. Its primary function is to engage enemy ships and other surface targets effectively. The Harpoon is a versatile anti-ship missile that can be launched from various platforms, including ships and aircraft, and it utilizes a sea-skimming flight profile to enhance its chances of evading radar detection while approaching its target. This design feature is integral to its effectiveness in naval warfare scenarios.

The other options do not accurately reflect the primary purpose or capabilities of the Harpoon missile. It is not intended for surface-to-air engagement, which is a different operational focus involving missiles designed to intercept aerial threats. Additionally, while the Harpoon can be used by submarines, it's not exclusively designated for that platform, as it can also be launched from surface ships and aircraft. Thus, the distinguishing characteristic of the Harpoon as a ship-launched missile aimed at surface targets is what makes the selected answer accurate.