Where does the overwhelming amount of seismic activity occur on the earth's surface

Orogeny is an event which causes large amounts of deformation in the earth's crust and upper mantle. These deformations occur due to the movement of tectonic plates and the result of the deformations are large amounts of seismic activity. The regions formed by these events are called orogens or orogenic belts.

The speed of  sound:   sound travels  at different speeds depending on what it istraveling through. of the three mediums (gas, liquid, and solid)  sound waves travel the slowest through  gases, faster  through  liquids, and fastest  through  solids.

3. is true i think i should be right