This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
[{'content': 'Feulgen reaction is used to test \nSelect and explain. \nA. mRNA, B. tRNA, C. DNA, D. SnRNA', 'role': 'user'}, {'content': 'Answer: C \nExplanation: DNA should be stained red. The background, if counterstained, is green. The Feulgen reaction is a semi-quantitative technique. If the only aldehydes remaining in the cell are those produced from the hydrolysis of DNA, then the technique is quantitative for DNA.', 'role': 'assistant'}]