The polymerase chain reaction:

• A. Doubles the template sequence of DNA with each cycle.
• B. Makes a single copy of the template sequence of DNA with each cycle.
• C. Is used to determine the sequence of a region of DNA.
• D. All are correct.

Answer: (A)

Verified step by step guidance

1. Understand the purpose of the Polymerase Chain Reaction (PCR): PCR is a technique used to amplify a specific segment of DNA, making millions of copies of a particular DNA sequence.
2. Identify the key components of PCR: These include the DNA template, primers, DNA polymerase, nucleotides, and a buffer solution.
3. Recognize the steps involved in PCR: The process involves denaturation (heating the DNA to separate strands), annealing (cooling to allow primers to bind to the template), and extension (DNA polymerase synthesizes new DNA strands).
4. Analyze the outcome of each PCR cycle: Each cycle of PCR doubles the amount of DNA, meaning the DNA sequence is exponentially amplified.
5. Evaluate the options given in the problem: Consider which statements accurately describe the PCR process, focusing on the amplification aspect and the purpose of PCR in DNA sequencing.