Option 1: Japan Sea - The Japan Sea is a marginal sea located between Japan and Korea. While it is known for its rich marine biodiversity, it is not considered the largest fishing ground in the world.

Option 2: North Sea - The North Sea is a marginal sea located between the United Kingdom, Germany, Denmark, Norway, and the Netherlands. It is famous for its productive commercial fishing grounds, making it a significant fishing area. With its large size and abundant fish stocks, the North Sea is indeed considered the largest fishing ground in the world.

Option 3: North-East Pacific - The North-East Pacific is a vast area of the Pacific Ocean, extending from the coast of North America to the northern part of the Pacific Rim. While it does have significant fisheries, it is not recognized as the largest fishing ground in the world.

Option 4: Newfoundland waters - Newfoundland waters are located off the eastern coast of Canada. While they are known for their rich fishing grounds and historically important cod fisheries, they are not considered the largest fishing ground in the world.

In conclusion, the correct answer is option 2 - North Sea, as it is globally recognized as the largest fishing ground.