Answer:
A. form where subduction takes place.
Step-by-step explanation:
Volcanic arcs -
It refers to the group of volcanoes , that are formed above the subducting plates , is referred to as volcanic arcs .
In most of the cases , they are formed from the subduction of an oceanic tectonic plate .
Various offshore volcanoes form island , referred to as the volcanic island arc.
Hence , from the given information of the question ,
The correct answer is A.