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: Medicine
Restriction endonuclease is : 
Select and explain. 
A. Break single stranded DNA, B. Break double stranded DNA, C. Break peptide chain, D. Break RNA
B: Break double stranded DNA
Answer: B: Break double stranded DNA 
Explanation: B i.e. Break double stranded DNA