The asthenosphere is composed of rock, but also has plasticity. this is because of
a. the crust
b. movement of the inner core
c. extreme heat and pressure
d. volcanoes that are present

It is because of volcanoes that are present. Because as known that volcanoes explode lava and magma that turn into rocks. And i think maybe at the end of the explosion when the smoke goes out of the volcano, this smoke makes them plasticity. so its D. :)

What are the choices?