This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
The term 'animalcules' to oral microorganisms is given by: 
Select and explain. 
A. W D Miller, B. Leeuwenhoek, C. Robertson, D. Socransky
B: Leeuwenhoek
Answer: B: Leeuwenhoek 
Explanation: Animalcule ('little animal', from Latin animal + the diminutive suffix -culum) is an old term for microscopic organisms that included bacteria, protozoans, and very small animals. 
The word was invented by Antonie van Leeuwenhoek to refer to the microorganisms he observed in rainwater.