Which of the following is an example of a biological hazard in food?

Biological hazards in food refer to microorganisms such as bacteria, viruses, and parasites that can contaminate food and lead to foodborne illnesses. These hazards are often the primary concern in food safety because they can cause serious health issues when ingested. For example, harmful bacteria like Salmonella or E. coli can multiply in food and pose significant health risks.

The other options mentioned involve different types of hazards. Chemical residues pertain to substances like pesticides or cleaning agents that may contaminate food, while sharp objects imply physical hazards that could cause injury. Pest droppings, while certainly a concern for contamination, fall under physical hazards or can be associated with the presence of pathogens, but they do not directly represent the biological aspect as distinctly as bacteria, viruses, and parasites do. Therefore, the option highlighting bacteria, viruses, and parasites accurately captures the definition of a biological hazard.