What is a depth charge used for?

A depth charge is a specialized explosive device designed specifically for underwater warfare, particularly used against submarines. It operates by being released into the water and detonating at a pre-determined depth, allowing it to maximize its effective blast radius against submerged threats. This capability to target submarines makes depth charges a valuable tool in naval warfare, enabling surface ships to engage submersible foes without requiring direct engagement.

The other choices describe different types of weaponry and their respective uses. For instance, surface explosives targeting ground troops do not have the underwater capabilities that depth charges possess, while bombs aimed at aircraft pertain to aerial combat operations. Similarly, an explosive delivered from a torpedo would not fit the specific characteristics and operational purpose of a depth charge, which is designed for detonation at depth rather than being launched from a torpedo platform. Thus, the unique function and design of the depth charge as an underwater bomb clearly differentiates it from other types of military ordnance.