Task: Class Definition Understanding (ontology: Earth_Environment/EnvironmentOntology)

Which of the following definitions best describes 'underground water'?

A. Water that is found on the surface of an astronomical object.
B. A liquid water which has no current or flow and is susceptible to contamination by pathogens or pathogenic vectors.
C. Water which has physicochemical properties determined by processes which occur beneath the planetary crust.
D. Underground water which is located in pore spaces found in rock or unconsolidated deposits such as soil, clay, or gravel.

Answer: Water which has physicochemical properties determined by processes which occur beneath the planetary crust.