Answer:
The increased temperature in this layer is due mainly to UV absorption by various chemical species, including ozone and molecular oxygen present in the stratosphere. Maximum heating takes place in the upper part of the stratosphere. Because of the stable air, pollutant mixing is suppressed within this layer.
Correct answer - Tetrahedral, planar or flat.
Why? - When carbon forms single bonds with other atoms, the shape is tetrahedral. When two carbon atoms form a double bond, the shape is planar, or flat. Single bonds, like those found in ethane, are able to rotate.