Hydraulic action, abrasion, attrition and solution are all types of what fluvial process

Hydraulic action, abrasion, attrition, and solution are all types of erosion.

Explanation: These processes describe how water and sediment interact with the riverbed and banks. Hydraulic action refers to the force of moving water breaking rocks apart, while abrasion involves particles scraping against the riverbed, wearing it down. Attrition occurs when rocks and stones collide with each other, becoming smaller and more rounded. Solution involves the chemical dissolution of soluble rocks in water. Together, these processes contribute to the shaping and deepening of river channels.