Which statement correctly describes alluvial deposits?

• A. They are formed by volcanic activity.
• B. They consist of stream-deposited particles.
• C. They are typically found in mountain streams.
• D. They contain only sediment from glaciers.

Answer: (B)

Alluvial deposits are primarily formed from the accumulation of sediment that has been transported and deposited by rivers and streams. This process involves the movement of materials like sand, silt, gravel, and clay, which are carried along by flowing water and ultimately settle in areas such as riverbanks, floodplains, and deltas. The term "alluvial" specifically refers to sediments that have been deposited by running water, highlighting the significance of water's role in shaping these deposits.

In contrast to the other statements, which suggest origins unrelated to flowing water, option B accurately captures the essence of alluvial deposits as being the result of stream-deposited particles. Alluvial deposits can vary in composition and granularity depending on the speed and volume of the water flow, demonstrating the dynamic nature of these sedimentary formations.