......always occur when a volcano erupts.?

Question

a earthquakes

b landslides

c lava flows

d volcanic ash release

Answer 1

since there is no all of the above go with earthquakes it's the most likely.

Answer 2

earthquakes.

Lava flows only occur with shield volcanoes, and volcanic ash is only released with andesitic erruptioins (like Mt. St. Helens) and rhyolitic explosions (though the ash would me mixed with pieces of the volcano as well).