Which of the following best describes a carbon sink?

A carbon sink is an area or a system that absorbs more carbon dioxide than it emits, playing a crucial role in mitigating climate change by reducing the concentration of greenhouse gases in the atmosphere. Forests, oceans, and soils are prime examples of carbon sinks. They take in carbon dioxide during processes like photosynthesis, thereby serving as a buffer against carbon emissions from human activities.

The other options do not accurately describe a carbon sink: a source of carbon emissions refers to areas that contribute to atmospheric CO2, a natural process producing carbon dioxide does not imply net absorption, and a process that accelerates climate change instead reflects activities that increase atmospheric greenhouse gases rather than reduce them. Therefore, the definition that clearly aligns with the role of carbon sinks in the carbon cycle is that they absorb more carbon than they release.