Final answer:
The immediate action should be to fully assess the situation for potential hazards, call for appropriate emergency assistance, and if safely trained to do so, provide first aid to the unconscious driver.
Step-by-step explanation:
The immediate action when encountering an overturned tanker truck with a leaking clear liquid and an unconscious bleeding driver is B) Fully assess the situation and request the appropriate assistance. It is essential to ensure personal safety and the safety of the victim by assessing hazards related to the chemical spill. Approach the scene carefully, and if you're trained and it's safe to do so, administer first aid to the injured driver. Simultaneously, call emergency services to inform them about the chemical spill and the medical emergency. Do not attempt to move the injured driver unless there is an immediate danger that requires it, as this could cause further injury.