This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Considerations - Infectious Diseases, Subject name: Pediatrics
[{'content': 'A 5-year-old unimmunized child presented with high fever, sore throat, dysphagia & voice change. Throat swab from a whitish lesion showed the following diagnosis. \nSelect and explain. \nA. Diphtheria, B. Mumps, C. Pertussis, D. Streptococcal pharyngitis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: a. DiphtheriaOn Albert staining, C. diphtheriae appears green colored rod shaped bacteria with bluish black metachromatic granules at the poles', 'role': 'assistant'}]