This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pathology
[{'content': 'Chemotaxis is \nSelect and explain. \nA. Unidirectional increase in movement, B. Random movement increase, C. Margintion of leucocytes, D. Increase of leucocytes', 'role': 'user'}, {'content': 'Answer: A \nExplanation: .', 'role': 'assistant'}]