Protecting the ocean environment is one of the coast guard's job.
Answer: Option 4.
Step-by-step explanation:
Coast guard is a person who makes sure that the tankers reach the safe water of a country in a safe way. Till the time the tankers of the country do not reach towards the safe water and touch the safe water of the country, the coast guard keeps an eyes on the tanker.
So the coast guard has to make sure that environment of the ocean is safe and protected and there is no threat of war in it. If there is any kind of threat, then he has to take some kind of action to protect it and act in a quick manner.