Which process is part of the water cycle?

• A. Transpiration
• B. Osmosis
• C. Evaporation
• D. Filtration

Answer: (C)

Evaporation is the process by which liquid water becomes water vapor, a central step in the cycle that moves moisture into the atmosphere. Sunlight heats bodies of water like oceans, rivers, and lakes, causing some water to escape as vapor. This vapor rises, cools, and condenses into clouds, leading to precipitation that returns water to the surface and sustains the cycle. Transpiration from plants also contributes water vapor, but that’s usually discussed as evapotranspiration; the direct, recognizable process in the cycle is evaporation. Osmosis involves water moving across a membrane, and filtration is a separation process—neither describes a stage of the natural water cycle.