Final answer:
Foodborne illnesses can occur through biological, chemical, and physical contamination. Biological contamination happens when microorganisms like bacteria, viruses, and parasites contaminate the food. Chemical contamination occurs when toxins are present, and physical contamination happens when foreign objects enter the food.
Step-by-step explanation:
Foodborne illnesses can occur through three main ways: biological, chemical, and physical contamination. Biological contamination happens when microorganisms such as bacteria, viruses, and parasites contaminate the food. Chemical contamination occurs when toxins or harmful chemicals are present in the food. Physical contamination happens when foreign objects like insects or cigarette butts accidentally get into the food.