The answer is D. the ocean.
The most of the water on Earth is held in the oceans, about 97% of all the water. The other 3% of the Earth water is freshwater - 2% belong to ice (glaciers) and 1% belong to ground water. Imagine you have one two-liter bottle filled with water. Let's it represent the whole water on the Earth. If you take only one tablespoon of water from the bottle, the water that remains in the bottle represents the amount of water in the oceans (97%). The water in the tablespoon represents freshwater (3%).