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': 'Oudin procedure is a immunodiffusion by \nSelect and explain. \nA. Single diffusion in one dimension, B. Double diffusions in one dimention, C. Single diffusion in two dimensions, D. Double diffusions in two dimensions.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Single diffusion in one dimension (Oudin Procedure).', 'role': 'assistant'}]