Question

composite volcanoes are known for being...
...fast - moving magma which builds a small amount of pressure and then the lava simply oozes out of the volcano at the vents.
...usually dormant, and rarely exploding volcanoes but when they do it is rather unspectacular and does not do much.
...violent and explosive eruptions that sometimes blow off a major part of a volcano.

Explanation:

To determine the correct description of composite volcanoes, we analyze each option:

• The first option describes a volcano with fast - moving (low - viscosity) magma that oozes out, which is characteristic of shield volcanoes, not composite volcanoes.
• The second option describes volcanoes that are usually dormant and have unimpressive eruptions, which does not match the nature of composite volcanoes.
• Composite volcanoes (also known as stratovolcanoes) are known for their violent and explosive eruptions. The magma in composite volcanoes is viscous, leading to the build - up of high pressure. When they erupt, it can be very violent, and sometimes parts of the volcano can be blown off.

Answer:

...violent and explosive eruptions that sometimes blow off a major part of a volcano.