Which type of organism is primarily studied in microbiology?

Microbiology is the branch of science that focuses on the study of microorganisms, which include bacteria, viruses, archaea, fungi, protozoa, and algae. This discipline examines their biology, pathology, and interactions with humans, other organisms, and the environment. The primary organisms of interest in this field are microorganisms because they are often too small to be seen without a microscope, and their roles in health, disease, and ecological systems are significant.

While fungi, plants, and animals are important for various biological and ecological studies, they are not the primary focus of microbiology. The term "microorganisms" encompasses all organisms studied within microbiology, making it the correct and most inclusive answer. This broad category is essential for understanding various processes, including diseases caused by pathogens, the benefits of beneficial microbes, and the overall dynamics of ecosystems.