Which component of sediment load is made up of sand-sized or larger particles that roll along the stream bottom?

The component of sediment load composed of sand-sized or larger particles that roll along the stream bottom is known as the bed load. This type of sediment transport occurs primarily near the streambed, where heavier particles are moved by the physical movement of water and may bounce or slide along the bottom due to the force of the current. Bed load is distinct from other types of sediment transport, as it involves particles that are too heavy to be suspended in the water column and therefore remain in contact with the streambed.

In contrast, dissolved load refers to minerals that are completely dissolved in water and carried along invisibly. Suspended load consists of particles that are lighter and small enough to be carried within the water column itself without settling to the bottom. Surface load, while not a standard term, may imply particles that rest on the water's surface and is not typically used to describe sediment transport in streams. Thus, bed load is the correct answer as it specifically denotes the movement of sand-sized or larger particles along the streambed.