Final answer:
Silt and clay particles are the sediments most likely to be transported as suspended load in a river, due to their small size and light weight allowing them to remain suspended in the water.
Step-by-step explanation:
The particles of sediment most likely to be transported as suspended load in a river are silt particles and clay particles. Suspended load refers to the fine-grained materials that are carried within the water column above the streambed. Due to the smaller size and lighter weight of silt and clay particles, they can remain suspended in the water for prolonged periods and be transported over great distances by the river flow. In contrast, larger and heavier particles such as gravel and sand tend to be transported along the riverbed in the form of bed load because they require more turbulent water to stay in suspension.