According to the Millennium Ecosystem Assessment (MA), ecosystem services are classified into four main categories:

Supporting Services: These are services necessary for the production of all other ecosystem services. Their impacts on people are often indirect or occur over a very long period. Examples include nutrient cycling, soil formation, and primary production.

Provisioning Services: These are the products obtained from ecosystems, such as the production of food and water (Option A), timber, and fiber.

Regulating Services: These are the benefits obtained from the regulation of ecosystem processes. Examples include the control of climate and disease (Option B), water purification, and crop pollination.

Cultural Services: These are non-material benefits people obtain from ecosystems through spiritual enrichment, recreation, and aesthetic experiences.

Option C is the correct answer because Nutrient cycling is a fundamental supporting service. While the official MA Synthesis Report (2005) classifies pollination as a regulating service, the inclusion of nutrient cycling makes Option C the only choice containing a primary supporting service.