The two mechanisms for water pollution are called direct and indirect (option B).
Explanation:
Water pollution can have multiple causes, which have been grouped into two categories - according to their source - direct and indirect.
Among the direct causes are wastes from manufacturing plants, waste treatment or refineries, which go to urban water supply sources.
Indirect causes of pollution come from environmental contaminants that fall through rain, or from contaminants that are found in the soil and filter into water sources.
All these pollutants come from human activity, so there is legislation for the control and prevention of water pollution for human consumption.
Regarding other options:
<em> </em><em><u>High and low, lethal and nonlethal or harmful and innocuous</u></em><em> do not constitute the classification of the causes of water pollution, although they can be useful to name the effects that this type of pollution produces.</em>
A blocked airway can kill someone in three to four minutes, but it can take more than eight minutes for an ambulance to arrive. So a simple procedure such as opening someone's airway can save their life whilst waiting for emergency help to arrive.
