Which of these is an example of an inorganic contaminant?

Fluoride is classified as an inorganic contaminant because it is a naturally occurring mineral that does not contain carbon-hydrogen bonds, which are characteristic of organic compounds. Inorganic contaminants typically include metals and other minerals that can dissolve in water, affecting its quality and safety for consumption. Fluoride is often discussed in the context of water supply because it is added to drinking water for its dental health benefits but can be a concern when present in excessive amounts.

In contrast, the other options listed primarily consist of organic compounds or substances. Herbicides are organic chemicals used in agriculture to control unwanted plants. Chlorine, while it can sometimes be debated as being inorganic due to its elemental form, is typically associated with organic compounds in its usage context, and organic solvents are purely organic substances used for dissolving other compounds. Hence, fluoride stands out as the correct example of an inorganic contaminant.