Sphere because of the sun orbit around the solar system
c.polluting a river because u are contaminating the water
A caldera is a large depression formed when a volcano erupts and collapses. During a volcanic eruption, magma present in the magma chamber underneath the volcano is expelled, often forcefully. When the magma chamber empties, the support that the magma had provided inside the chamber disappears.
Answer:wild fires
Explanation:wild fires clear away dead grass and trees