The correct answer is B) Pick up other survivors. The first priority when boarding an inflatable liferaft is to ensure the safety and survival of all persons in the water. This means quickly locating and bringing aboard any other survivors in the vicinity, as they may be injured or incapacitated. Posting a lookout or opening equipment packs can wait until the raft is fully occupied. Issuing seasickness medication, while important, is a lower priority than ensuring everyone is safely aboard the liferaft first. The regulations and training for liferaft operations emphasize the immediate rescue of all survivors as the critical first step.