The largest ocean in the world is the Pacific Ocean, which is option 4. The Pacific Ocean covers an area of about 63,800,000 square miles, making it larger than all the other oceans combined. It is located between Asia and the Americas, bordered by the Arctic and Southern Oceans.

Option 1, the Atlantic Ocean, is the second-largest ocean with an area of about 41,100,000 square miles. It is positioned between the Americas and Europe/Africa.

Option 2, the Indian Ocean, is the third-largest ocean with an area of about 27,200,000 square miles. It is located between Africa, Asia, and Australia.

Option 3, the Arctic Ocean, is the smallest and shallowest ocean with an area of about 5,400,000 square miles. It is situated in the Arctic Circle region, around the North Pole.

Therefore, the correct answer is option 4.