Final answer:
Of the options provided, a sanitizer can cause chemical contamination by introducing potentially harmful chemicals into food if not used or rinsed properly.
Step-by-step explanation:
Chemical contamination refers to the presence of chemical substances that can be harmful if ingested or come into contact with humans. In the context of food safety, chemical contaminants can originate from various sources. Of the options provided, sanitizer is the one that can cause chemical contamination. Sanitizers are used to reduce bacterial contamination to safe levels, but if not used properly, they can become a contaminant themselves. For instance, if a sanitizer is not correctly rinsed off surfaces that come in contact with food, it can contaminate the food with chemicals that are not safe for consumption. Other forms of contamination mentioned, such as an earring (physical hazard), Salmonella (biological hazard), and mold (which might produce toxins, a subset of chemical hazards), do not fall under the specific category of chemical contaminants in the context provided.