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
Feulgen reaction is used to test 
Select and explain. 
A. mRNA, B. tRNA, C. DNA, D. SnRNA
C: DNA
Answer: C: DNA 
Explanation: 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.