Which statement is true regarding protozoa?

Protozoa are a diverse group of single-celled organisms that typically exhibit motility, allowing them to move around in their environments. This movement is often facilitated by structures such as flagella, cilia, or pseudopodia. Their unicellular nature is a defining characteristic, setting them apart from multicellular organisms. Protozoa can thrive in various habitats, including soil, freshwater, and marine environments, and they play significant roles in ecological systems, including as decomposers and as part of the food web.

The other statements do not accurately reflect the characteristics of protozoa. They are not multicellular or immobile; many species can reproduce both asexually and sexually, and while some protozoa can be pathogenic and cause diseases, many are harmless or even beneficial. As such, the description of protozoa as single-celled and capable of movement is indeed accurate.