Answer: A. Frequent earthquakes may occur volcanic activity may be common.
When the plates of the continents and oceans collides, the thin and dense oceanic plate submerged under the thick and less dense continental plate. This process is called as subduction. As the oceanic plate submerged down the earth crust it is exposed to the hot magma. The melting of the subducted plate occurs and this results in the high intensity volcanic eruption and frequent earthquakes.
