Why is it critical to plan dives according to dive tables or a dive computer?

Planning dives according to dive tables or a dive computer is essential primarily to manage depth and time effectively, which significantly minimizes the risks associated with decompression sickness (DCS). DCS occurs when a diver ascends too quickly, leading to the formation of nitrogen bubbles in the bloodstream and tissues as the pressure decreases.

Dive tables and dive computers provide critical information regarding safe limits for time spent at specific depths. They calculate no-decompression limits (NDLs) and allow divers to make informed decisions about their ascent rates, as well as to determine required safety stops to off-gas excess nitrogen safely. By adhering to these guidelines, divers help protect themselves from potentially life-threatening conditions associated with rapid pressure changes.

While other answers touch on aspects of diving enjoyment or efficiency, the primary focus of diving safety is ensuring that divers adhere to protocols that prevent DCS, making choice C the most accurate and relevant answer.