Which organism uses spores to reproduce?

Fungi are unique among the organisms listed because they utilize spores as their primary means of reproduction. This method allows them to spread and colonize new environments effectively. Spores are often produced in large quantities and can remain dormant for extended periods, surviving unfavorable conditions until they find a suitable environment to germinate.

Bacteria typically reproduce asexually through binary fission instead of using spores. Viruses do not reproduce by means of spores; they require a host cell to replicate. Protozoa, while they can reproduce in various ways, commonly use methods such as binary fission or budding, rather than spores. Thus, fungi stand out as the definitive organisms that reproduce through spores, making them the correct choice in this question.