This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Techniques in molecular biology, Subject name: Biochemistry
All of the following are used in a PCR reaction, EXCEPT 
Select and explain. 
A. Buffer, B. ddNTPs, C. Oligonucleotide Primer pair, D. Template DNA
B: ddNTPs
Answer: B: ddNTPs 
Explanation: Components of PCR 1. Template DNA 2. Pair of DNA Primers 3. Thermostable DNA polymerase 4. dNTPs 5. Buffer with divalent cation ddNTP (dideoxynucleotide triphosphates) Not used in PCR; Used in sanger's chain-termination method