Option (1) is the correct answer because separation of DNA fragments which is carried out after restriction enzyme digestion, is done by a technique known as gel electrophoresis.

Option (2) is not the correct answer because polymerase chain reaction (PCR) is a technique used for amplification of gene of interest.

Option (3) is not the correct answer because recombinant DNA technology comprises altering genetic material outside an organism to obtain enhanced and desired characteristics in living organisms or as their products.

Option (4) is not the answer because Southern blotting is a method used for detection of specific DNA sequences in samples.