Final answer:
The correct answer is (a) Bacteria. Bacteria can grow at refrigerator temperatures and may produce toxins that lead to foodborne illnesses. Refrigeration does not kill bacteria; it simply inhibits their growth.
Step-by-step explanation:
The type of microorganism that grows at fridge temperatures, may produce toxins, and is transferred via air currents is (a) Bacteria. Although refrigeration slows microbial metabolism and growth, it does not kill bacteria. Some bacteria, known as psychrophiles, prefer cold temperatures and can grow in refrigerated environments. These bacteria can cause foodborne illnesses if they produce toxins in food that are not destroyed by cooking.
Appropriate food safety practices, including cooking foods to safe internal temperatures and preventing cross-contamination, are vital in preventing illness from these bacteria. Regulatory agencies require routine testing to protect the public from foodborne diseases caused by microorganisms such as bacteria, parasites, and viruses. It is important to note that placing food in a refrigerator does not kill bacteria; it merely slows their growth.