1. the tropopause is
the layer of high ozone concentration
the layer between tropical and polar air

the boundary between the troposphere and stratosphere
the area between earth's surface and the atmosphere

Tropopause is the boundary between the troposphere and stratosphere.

Explanation:

Tropopause marks the transition region between troposphere and stratosphere.As we move up from the Earths surface , the temperature gets colder but when we reach the tropopause the temperature becomes constant and the temperature does not fall further.It is at a height of about 9Km at the polar region while at a height of 17 Km at the equitorial region.