Separation of DNA fragments is done by a technique known as 

Gel electrophoresis is a widely used technique to separate DNA fragments based on their size and charge. DNA samples are loaded onto a porous gel matrix, and an electric field is applied, causing the DNA fragments to migrate through the gel. Smaller DNA fragments move faster and travel farther through the gel, leading to
their separation based on size. 

(1) Polymerase chain reaction (PCR) is a technique used to amplify specific regions of DNA through repeated
cycles of denaturation, annealing and extension using DNA polymerase. In the context of DNA fingerprinting, PCR is used to amplify DNA of sample. 

(2) Recombinant technology involves the manipulation of DNA to create recombinant DNA molecules, which
may contain DNA from different sources. While this technology is used in genetic engineering, it does not
specifically pertain to the separation of DNA fragments.

(3) Southern blotting involves the transfer of separated DNA fragments on a gel to an inert membrane.