Answer: C.ecosystem services
Step-by-step explanation:
The ecosystem services are the benefits that are received by human kind from the natural environment. These benefits includes the forest ecosystem, aquatic ecosystem and grassland ecosystem.
The chemicals, medicines, food and water are the services that human kind receives from ecosystems. The natural ecosystems are also responsible for controlling the disease, climate and nutrient cycles, aids in the production of oxygen and also aids in maintaining the recreational benefits.
The pharmaceutical products obtain from the wild life are also the sources of ecosystem services.