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
In PCR: 
Select and explain. 
A. Thermostable enzyme is needed, B. 211 copies formed after 'n' numbers of multiple, C. Non specific, D. Thermolabile enzyme
A: Thermostable enzyme is needed
Answer: A: Thermostable enzyme is needed 
Explanation: A i.e. Thermostable enzyme is needed