How does groundwater become polluted

Groundwater becomes polluted when toxins or pollutants are emitted into the ground, or surface water that then leeches through soil and enters the groundwater. Groundwater is often located beneath the earth at varying depths, but when pollutants or toxins pass through the earth to reach these groundwater sources they then often become polluted. There are also processes such as mining for minerals, oil, or natural gas where chemicals or the resources themselves are released into the groundwater through the extraction process that then thereby pollute the groundwater. 

Ithink d would be correct