What kingdom is characterized as lower plants?

The correct choice is fungi, which are often referred to as lower plants due to their simple structure and non-vascular nature. They do not possess the typical features associated with higher plants, such as roots, stems, and leaves. Fungi play an essential role in ecosystems, primarily as decomposers, breaking down organic material and recycling nutrients back into the environment.

In understanding fungi as "lower plants," it's important to recognize that they belong to a separate kingdom from true plants (Kingdom Plantae). While they share some characteristics with plants, such as being multicellular and having cell walls, fungi have unique features, like the composition of their cell walls made from chitin rather than cellulose, which is found in true plants.

The other choices represent distinct groups: Eubacteria, which are prokaryotic organisms without a nuclear membrane; protozoa, which are mostly single-celled eukaryotic organisms; and a repetition of fungi, which clarifies their importance in this context as lower plants due to their simpler and more primitive characteristics compared to higher plants.