What does GLORIA stand for and what is its unique feature?

GLORIA stands for Geological Long-range Inclined Acoustical instrument. Its unique feature lies in its ability to be towed behind a ship. This towed system allows for efficient gathering of data over extensive areas of the seafloor by utilizing acoustic signals to map geological features at great distances from the vessel. The design maximizes coverage and resolution of the seabed while allowing the ship to maintain speed, making it a valuable tool in hydrographic surveying and geological mapping.

The other options present alternatives that are not accurate or reflective of GLORIA's capabilities, thus reinforcing why the chosen answer is the most appropriate. For instance, while surface mapping is a feature of various instruments, the capability to be towed is a defining factor that distinguishes GLORIA from others in the context given.