Which type of biological contaminant multiplies only in living things?

The correct answer is that viruses are classified as biological contaminants that multiply only in living things. Viruses are unique among biological contaminants because they cannot replicate on their own; they need to invade a host cell to reproduce. This characteristic is key for understanding the behavior of viruses in food safety, as they rely on living organisms—such as humans, animals, or plants—for propagation.

Parasites, while also living organisms, have complex life cycles that can involve hosts and environments outside of living things. Bacteria are capable of multiplying in various environments, including food and surfaces, as they do not require a living host to reproduce. Fungi, which include molds and yeasts, can grow on organic materials without needing a live host, making them distinct from viruses. Understanding these elements is vital for food safety management to effectively prevent and control biological contamination.