The correct answer is option 3: on the islands. This means that volcanoes are primarily found on islands. Islands are formed through various geological processes, one of which is volcanic activity. When tectonic plates collide or separate, magma from the Earth`s mantle can rise to the surface, forming volcanic eruptions. This can happen in areas where tectonic plates meet and create underwater mountain ranges, such as the Ring of Fire, or in regions with hotspot activity, like Hawaii. Volcanoes can also be found along coastlines if the coastline is part of an island or if there are underwater volcanic formations near the coast. While volcanoes can be found in different parts of the world, option 3 specifically highlights their prevalence on islands.