Final answer:
Microbiology is the study of microbes, encompassing various subfields and including the study of the microbiota, which refers to all microorganisms in a symbiotic relationship.
Step-by-step explanation:
The study of small living organisms called microbes is known as microbiology. It is a branch of science that investigates the biology of microscopic organisms, often requiring the use of a microscope to directly observe their shapes and activities. Microbiologists explore various aspects of these organisms, such as metabolism, genetics, and their interactions with the environment. They may specialize in subfields such as bacteriology (the study of bacteria), mycology (the study of fungi), or virology (the study of viruses).
To answer the multiple choice question, the correct term describing the study of microbes is d. microbiology. As for the term microbiota, it refers to all of the microorganisms involved in a symbiotic relationship, which includes bacteria, viruses, fungi, and other microscopic life forms that coexist within a specific environment, such as the human body.