Answer:
A
Step-by-step explanation:
The particles of sediment that are most likely to be transported as suspended load are small, low-density particles. These particles have a small enough size and low enough density to be easily carried along by the flow of water or air without settling out too quickly.
Pebbles of average density (Option B) are too large and heavy to be transported as suspended load. Instead, they are typically transported as bed load or rolled along the bottom of a river or stream.
Sand and gravel of relatively high density (Option C) can be transported as suspended load in very fast-moving water, such as during floods or other high-energy events. However, they are more likely to be transported as bed load.
Dissolved ions in solution (Option D) are not considered sediment and are transported as part of the water itself, not as suspended load.
Therefore, the correct answer is Option A: small, low density particles.