In the united states, where can volcanoes like those at b be found?

Volcano along the pacific coasts as the cascades mountains.

Explanation:

The diagram shows the oceanic plate as the pacific plate and it is submerged under the North American plate and the other end being the divergent boundary that is formation of a new plate like that of the mid-Atlantic ridge and thus the lighter plate is overriding the heavier plate and the formation of a convergence zone leads to the cascades mountains that are form part of the pacific ocean.