The correct answer is option A – Primer bind to the newly separated DNA strand. Polymerase Chain Reaction is a lab technique that is used in generating thousands to millions of copies of a specific section of DNA. In Polymerase Chain Reaction (PCR), there are three major steps. These are the denaturation step, annealing step, and the extension (elongation) step. In the annealing step, the temperature is lowered to about 50 to 60 degrees Celsius. This will allow primers to attach to specific regions on the DNA through hydrogen bonding.
The annealing step takes about 10 to 20 seconds to complete. The primer is made up of either DNA or RNA sequence of 20 to 30 base s in length. The primer marks the starting point for the synthesis of DNA, and they are complementary to the specific DNA segment to be copied.