Which technique is primarily utilized for amplifying DNA in vitro?

The technique primarily utilized for amplifying DNA in vitro is Polymerase Chain Reaction (PCR). PCR is a powerful and widely used method that allows for the rapid replication of specific DNA sequences. This amplification process involves repeated cycles of denaturing the DNA strands, annealing primers to the target DNA sequence, and extending the new DNA strands with a DNA polymerase enzyme. These cycles result in an exponential increase in the number of copies of the desired DNA segment, making PCR an essential tool in various applications, such as genetic testing, forensics, cloning, and research.

Other methods listed are not designed for DNA amplification. SDS-PAGE is primarily used for separating proteins based on their size. Western Blotting is a technique that involves the identification of specific proteins in a sample. Electrophoresis, while a method used to separate nucleic acids or proteins based on their size, does not amplify DNA; it merely sorts them for further analysis. Thus, PCR stands out as the specific method designed for in vitro DNA amplification.