This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
Restriction enzymes have been found in 
Select and explain. 
A. Bacteriophages, B. Bacteria, C. Fishes, D. Humans
B: Bacteria
Answer: B: Bacteria 
Explanation: A restriction enzyme or restriction endonuclease cleaves DNA into fragments at or near specific recognition sites within the molecule known as restriction sites. These enzymes are found in bacteria and provide a defence mechanism against invading viruses. Ref: Biochemistry by U. Satyanarayana 3rd edition Pgno : 579