Explanation

In the five-kingdom system, viruses are not placed in any of the five kingdoms:

1. Monera (bacteria)
2. Protista (eukaryotic organisms)
3. Plantae (plants)
4. Animalia (animals)
5. Fungi (fungi)

Viruses are considered non-living entities.

So, in the five-kingdom system, viruses are not classified in any of the five kingdoms.