Answer
A. As two oceanic plates come together, one plate may sink and slide beneath the other causing underwater volcanoes to form. The volcanoes will build up and gradually extend above the water’s surface forming islands.
Step-by-step explanation
The Islands are formed through the subduction process where the oceanic and continental plates converge. The dense and less thick oceanic plate is forced under the continental plate. The plate gets hotter the deeper it is pushed. When the plate reaches a depth facilitating the melting point, a molten rock is formed and it rises to the surface as forming a new volcano on the continental plate.