This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
[{'content': "Which of the following is not true about Corynebacterium diphtheria? \nSelect and explain. \nA. Deep invasion is not seen, B. Elek's test is done for toxigenicity, C. Metachromatic granules are seen, D. Toxigenicity is mediated by chromosomal change", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Diphtheria acts by its toxin and invasion are not seen. Elec gel precipitation test is done for determination of pathogenicity of diphtheria. Metachromatic granules are seen also called as Babes earnest granules. Bacteriophages (extra-chromosomal) are responsible for toxigenicity by phage conversion. Ref: Ananthanarayana textbook of Microbiology 9th edition Pgno : 236', 'role': 'assistant'}]