A.I. Explanation:

Option 1: "The surface water of the earth is covered with it."

Explanation: This option is incorrect because the text does not state that the surface water is covered with plankton. Instead, it mentions that plankton is a floating population in the ocean's surface water, which implies presence but not coverage.

Option 2: "Aquatic creatures depend on it for their survival."

Explanation: This option is correct as the text indicates that all marine life depends directly or indirectly on plankton. This aligns with the idea that aquatic creatures rely on plankton for their food supply, as plankton transforms inorganic materials into organic foodstuffs.

Option 3: "Plankton produces inorganic substances in the environment."

Explanation: This option is incorrect because the text states that plankton transforms inorganic components into organic substances (fat, protein, carbohydrates), not that it produces inorganic substances. This misrepresents the role of plankton.

Option 4: "Man and all land animals depend ultimately for their food supply upon it."

Explanation: This option is incorrect because while the text discusses how land animals depend on plants for food, it does not state that they depend on plankton. The focus is on marine life's dependence on plankton, not land animals.