What type of front is represented by the third symbol in the image

Stationary fronts

Explanation:

This a pair of air mass that is neither strong nor weak to replace each other thus waves tend to move along the frontal boundary. A wide variety of fronts are formed in this boundary as usual clouds and precipitation rainfall, here is a lot of water vapor in air masses. These masses either displayed or become shear lines when density contrasts with the frontal boundaries. Usually as a result of temperature equalizations. where narrow zones of winds shift persist for a time.  Occasionally, cold and warm airflow parallel to the frontal direction and the position may not move any further. The slope of the stationary wave is gentle.

Because some people pollute water ans waste it