This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Types of Genetic Disorders, Subject name: Pediatrics
[{'content': 'F body is? \nSelect and explain. \nA. Y chromatin, B. X chromatin, C. Chromosome 1, D. Chromosome 21', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Quinacrine, a fluorescence dye, binds strongly to Y chromosome forming a bright fluorescent spot (F body).', 'role': 'assistant'}]