What does hydrology study?

Hydrology is the scientific study focused specifically on water in all its forms. It encompasses the distribution, movement, and properties of water in the atmosphere and on the earth's surface. This includes understanding how water cycles through the environment, including processes such as precipitation, evaporation, and infiltration, as well as studying groundwater and surface water interactions.

The study of hydrology is vital for managing water resources, predicting floods, understanding droughts, and analyzing the sustainability of various ecosystems that depend on water. The correct answer highlights the comprehensive nature of hydrology as it relates to both the physical characteristics of water and its dynamic interactions within the environment.

In contrast to the other options, hydrology does not focus on the effects of pollution on ecosystems, which is a more ecological concern, nor does it deal directly with geological materials or weather patterns, although those areas can be influenced by hydrological studies. Thus, option C precisely defines the scope of hydrology as a discipline.