Which of the following is a function of a buoyancy compensator?

A buoyancy compensator, or buoyancy control device (BCD), is essential for a diver's ability to maintain neutral buoyancy and control their ascent and descent in the water. One of its primary functions is indeed acting as an attachment point for various pieces of dive gear. This allows divers to securely fasten their tanks, weights, and other necessary equipment, which helps ensure that all their gear is organized and accessible during the dive.

While the other options mentioned may pertain to the overall diving experience or equipment, they do not capture the primary function of a buoyancy compensator. For instance, providing thermal insulation is typically the role of wetsuits or drysuits, which are designed to retain body heat in cold water. Regulating air supply is related to the regulator, which delivers breathing gas from the tank to the diver, and automatic depth measurement is a function of dive computers or gauges, not a buoyancy compensator. Thus, the role of the buoyancy compensator as an attachment point for gear is integral to its design and functionality in scuba diving.