Which type of mine is deployed in the water column?

A moored mine is specifically designed to be deployed in the water column, typically suspended at a predetermined depth by cables or anchors. The mine remains stationary in relation to the ocean floor but is not resting on it like a bottom mine. Instead, its placement makes it effective against vessels that pass above its position. This strategic deployment allows moored mines to detect and engage targets more effectively without influencing the surrounding waters directly, maximizing their destructive potential while minimizing detection from vessels.

In contrast, drifting mines are designed to float freely in the water, allowing ocean currents to dictate their movement. Floating mines also remain on the surface, while bottom mines are anchored to the seafloor and do not occupy the water column at all. Thus, the characteristics and intended use of each type clearly differentiate the moored mine as the correct answer to the question posed, as it is the only one specifically situated in the water column.