C. Community . I took environmental science last year
Well, if it's an environmental community: Erosion changes the shape of the landscape. New plants grow in, small streams may form. New creatures moving in may also shape the community over time.
In a civilized community: New people in power, of course. Also, new people moving in and out. Hope I helped!
Answer : Because producers They make food for other organisms
Explanation
Prevents the water from contaminating our rivers, lakes and groundwater.