Pesticides ,manure and human hair are common contaminants ,critically discuss how food is contaminated in this three different ways

Manure is a common contaminate usually during the growing process of plants (especially because of use as fertilizer). Pesticides can also contaminate food both when grown or during processing, especially when not separated from things like rat poison. Human hair can contaminate food in both ways, but it also get into food during preparation if not in a hair net. 

The answer is either 3 or 4