The correct answer is A) Search for survivors. In an emergency situation where individuals have had to board a life raft, the first priority should be to check for any other survivors in the water and bring them into the raft. This is in accordance with standard maritime safety protocols, as ensuring the safety and rescue of all personnel takes precedence over other immediate concerns. The other answer choices, while important considerations, should come after the initial search for survivors. Determining position and closest land, rationing supplies, and checking emergency equipment are all crucial next steps, but cannot be properly addressed until all individuals have been accounted for and brought to safety within the life raft.