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

According to the given diagram, the location B represents an oceanic trench.

When a denser oceanic plate sinks below a less dense continental plate, it results in the formation of a subduction zone and is marked by a deep sea trench. This trenches are very long, narrow and deep and this forms the boundary between a continental and an oceanic plate. The subducting plate undergoes partial melting at greater depth and allows the magma to rise up towards the over-riding plate, giving rise to the formation of volcano or chain of volcanic islands.

Thus, in the figure, B represents a deep-sea oceanic trench.

a). in this case, dh> 0 and sd> 0. if t becomes larger, the term "-tds" will become more negative. at some point, it is possible that -dts will be more negative than the dh is positive, and the reaction will become spontaneous. this is probably the correct answer, but you should look at all of the other possibilities and make sure of that.