Of the following, which is the process by which rocks are broken down into smaller pieces through contact with air and water?

Deposition refers to the geological process where sediments, soil, and rocks are added to a landform or landmass. This occurs when the transporting medium—such as water, wind, or ice—loses energy and can no longer carry its load. While related to sedimentary processes, deposition does not involve the breakdown of rocks, making it an incorrect choice for this question.

Precipitation describes the process where water vapor condenses in the atmosphere and falls to the Earth as rain, snow, sleet, or hail. While precipitation is crucial for weathering, it is not a direct process of breaking down rocks; rather, it is a climatic phenomenon that can contribute to weathering but does not define it.

Sedimentation is the process by which particles settle out of a fluid and accumulate as sediment. Although it involves the accumulation of weathered material, it is distinct from weathering itself, which is the initial breakdown of rocks into smaller pieces. Sedimentation occurs after weathering has taken place, making this option incorrect.