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
[{'content': 'Which of the following is associated with Antonie van Leeuwenhoek which became a cornerstone in microbiology? \nSelect and explain. \nA. Telescope, B. Microscope, C. Stains, D. Immunization', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Antonie van Leeuwenhoek first observed and repoed bacteria. Using his handcrafted microscopes, he was the first to observe and describe single-celled organisms, which he originally referred to as animalcules, and which we now refer to as microorganisms. Ref: Textbook of Microbiology by Ananthanarayan, 6th edition, Page 1.', 'role': 'assistant'}]