What is the letter group designation after a dive to 60 feet for 30 minutes?

The correct letter group designation after a dive to 60 feet for 30 minutes is C, which aligns with how the RDP (Recreational Dive Planner) categorizes dive profiles for potential off-gassing and safety.

After completing a dive, divers are assigned a letter group based on the depth and duration of their dive, which helps determine the appropriate surface interval before the next dive. A dive to 60 feet for 30 minutes typically results in this letter group due to the calculations involving the depth, time spent underwater, and the body's nitrogen absorption and elimination rates. The RDP table indicates that spending this specific duration at this depth would place you in group C, which is important for planning subsequent dives and ensuring that the diver stays within safe limits for nitrogen loading.

Understanding that the letter group directly relates to how much nitrogen the body has absorbed can help divers avoid decompression sickness by allowing enough time for off-gassing. The other options, while potential outcomes based on different combinations of depth and duration, do not correspond to the given dive profile of 60 feet for 30 minutes and would therefore not be applicable in this context.