Volcanoes erupt when molten rock called magma rises to the surface. ... As the magma rises, bubbles of gas form inside it. Runny magma erupts through openings or vents in the earth's crust before flowing onto its surface as lava. If magma is thick, gas bubbles cannot easily escape and pressure builds up as the magma rises.

hope it helps..

Answer:

Mam, The instructions specifically said "From the activity "YOU" performed

Explanation:

(we do not know what activity you did so we can't do much but ask you to do it yourself)