This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Systemic Bacteriology (Gram Positive Bacilli, Gram Negative Bacilli), Subject name: Microbiology
[{'content': 'Pyoverdin is produced by : \nSelect and explain. \nA. Pseudomonas aeruginosa, B. Clostridium perfringenes, C. Bacillus stearothermophilus, D. Salmonella typhi', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Pyoverdin is green coloured diffusible pigment produce by Pseudomonas aeruginosa Other pigments are:- Pyocyanin - Blue Pyorubin - Red Pyomelanin - Black', 'role': 'assistant'}]