Final answer:
The term NOT used to describe microscopic organisms is Vertebrates.
Step-by-step explanation:
The correct answer is B) Vertebrates.
Microscopic organisms are commonly referred to as microorganisms or microbes. These terms are used to describe living organisms that are generally too small to be seen without a microscope. However, vertebrates are not microscopic organisms. They are a group of animals that have a backbone or spinal column, and they include animals like fish, amphibians, reptiles, birds, and mammals.