Final answer:
Volcanoes in the 'Ring of Fire' are most likely to form near subduction zones around the Pacific Plate, where intense tectonic activity leads to the formation of magma and subsequent volcanic eruptions.
Step-by-step explanation:
In the 'Ring of Fire', volcanoes are most likely to form in regions near subduction zones, which are areas where one tectonic plate moves under another and is forced to sink due to gravity into the mantle. Volcanoes can also form along oceanic ridges and in regions where continental plates are colliding. However, the specific area around the Pacific Plate is particularly known for its intense tectonic activity, leading to a high frequency of volcanic eruptions. The partial melting of the asthenosphere above the subducting slab at these zones leads to magma formation, which can create volcanoes.
While divergent plate boundaries, like the mid-ocean ridges, do involve the rise of magma, the Ring of Fire's volcanic activity is predominantly associated with the edges of the Pacific Plate, where subduction predominantly occurs. For example, the Pacific coast of the United States has several active volcanoes, like Mount St. Helens, that were formed due to subduction processes. It's important to note that transform boundaries, such as the San Andreas Fault, generally do not create volcanoes, as they are characterized by two tectonic plates sliding past each other horizontally.