What situation exemplifies chemical contamination?

Chemical contamination occurs when harmful substances are introduced into food, posing a risk to health. Preparing acidic food in a copper pot exemplifies this type of contamination because acidic foods can react with copper, leading to the leaching of copper into the food. Copper ingestion can result in foodborne illness and toxicity, marking a clear case of chemical contamination.

In contrast, using a dirty cutting board relates to biological contamination, as it may harbor pathogens. Storing food improperly is connected to physical contamination or spoilage, impacting food safety. Cross-contaminating raw and cooked food primarily involves biological hazards, as it facilitates the transfer of bacteria or viruses from raw foods to cooked items, increasing the risk of foodborne illness. The specific reaction of acidic foods with copper highlights the nature of chemical contamination, making it a clear answer.