Answer:
a. deep-sea trench and continental arc
Explanation:
When an oceanic tectonic plate and continental tectonic plate meet, they create a subsuction zone. Basically, the denser oceanic plate is moving below the continental plate, moving downward toward the mantle where it gets melted. On the boundary itself, a deep-sea trench forms, which is a very deep, very steep, part of the sea which is very active geologically. Also, another trade mark feature is the formation of continental arc, which is a chain of volcanoes on the edge of the continental plate, forming because of the rising magma from the mantle layer.
