Final answer:
Divergent boundaries produce the greatest volume of lava.
Step-by-step explanation:
The type of boundary that produces the greatest volume of lava is a divergent boundary. Divergent boundaries occur where two tectonic plates move apart, allowing magma from the mantle to rise up and fill the gap. This magma then solidifies and forms new crust, creating underwater mountain ranges called mid-ocean ridges.
One example of this is the Mid-Atlantic Ridge. These volcanic eruptions at divergent boundaries can produce enormous amounts of lava, leading to the formation of extensive lava plains.