The two important processes in the formation of volcanic arcs at the edge of continental plates are:
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Subduction - This is the process where one tectonic plate moves under another and sinks into the mantle, leading to melting of the subducted plate and resulting in volcanic activity.
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Uplift - This process can occur as a result of volcanic activity and the accumulation of volcanic material, contributing to the formation of elevation in volcanic arcs.
So the correct answers are subduction and uplift.