What pollution source is characterized by many diffuse contributors?

The correct choice highlights the nature of non-point source pollution, which is characterized by multiple diffuse contributors that are not easily traced to a single origin. This type of pollution typically arises from various land uses and activities, such as agricultural runoff, urban runoff, and atmospheric deposition, which collectively contribute to the degradation of water quality across larger areas.

In contrast, point source pollution originates from a specific, identifiable source, such as a discharge pipe from a wastewater treatment facility or a factory. The distinction is important in regulatory and remediation efforts, as non-point sources can be more challenging to control and manage due to their widespread and variable nature.

Groundwater refers to the water located beneath the earth's surface in soil pores and cracks, which can be contaminated by pollutants but does not itself describe a pollution source category like point and non-point sources do. Surface water pertains to bodies of water such as rivers, lakes, and oceans, which can be affected by both point and non-point source pollution but does not describe the nature of the pollution's contributors.