This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
[{'content': 'Generation time of E-coli is \nSelect and explain. \nA. 20 days, B. 20 minutes, C. 20 hours, D. 20 second', 'role': 'user'}, {'content': 'Answer: B \nExplanation: (20 minute) (271- Ananthanarayan 8th, 30- Chakrahorthy 2nd)* Many bacteria reproduce by binary fission and the average time required for the population, or the biomass, to double is known as generation time or doubling time.GENERATION TIME* Lepra bacillus - 24 Days* Tuberculous bacillus - 20 hours* Coliform E.coli - 20 minute* Clostridium - 10 minute* Each bacterial colony in a solid medium consists of descendants of a single cell* An ordinary bacterium doubles every 20-30 minutes and by geometric progression in exponential phase of growth thus a single bacterium can theoretically give rise to 1021 progeny in 24 hours roughly a ton of dry weight of bacterial cells.', 'role': 'assistant'}]