The figure below shows three steps (A, B, C) of Polymerase Chain Reaction (PCR). Select the option giving correct identification together with what it represents?                 

Options:
1. B - Denaturation at a temperature of about 98°C separating the two DNA strands.
2. A - Denaturation at a temperature of about 50°C
3. C - Extension in the presence of heat-stable DNA polymerase
4. A - Annealing with two sets of primers