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': 'Ouchterlony procedure is a immunodiffusion by \nSelect and explain. \nA. Single diffusion in one dimension, B. Double diffusion in one dimension, C. Single diffusion in two dimensions, D. Double diffusion in two dimensions', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Single diffusion in one dimension - Oudin procedure\nDouble diffusion in one dimension - Oakley fulthorpe procedure\nSingle diffusion in two dimensions - Radial immunodiffusion\nDouble diffusion in two dimensions - Ouchterlony procedure', 'role': 'assistant'}]