The correct option is
C Electrophoresis
Gel electrophoresis is a laboratory technique based on the principle of movement of charged particles towards oppositely charged electrodes under the influence of electric field. This is used for the separation of a mixture of DNA (a negatively charged molecule) fragments of varying sizes on agarose gel (a natural biopolymer) matrix under the influence of an electric field.
The negatively charged DNA molecule moves from the negative terminal of the gel towards the positive terminal. The distance migrated by the DNA fragment depends on the size of the molecule. DNA with more base pairs can migrate to shorter distances than those with a lesser number of base pairs in a gel of a particular composition. Besides, the rate of migration is also determined by the pore size of the gel.
The DNA fragments after separation form bands at different positions in the lane. These bands can be observed by using ethidium bromide as a stain and subsequently exposing the gel to ultraviolet light.
Restriction digestion is a technique used in molecular biology to cut DNA molecules with the help of restriction enzymes. These enzymes are endonucleases that recognise specific sites and cleave the phosphodiester bonds present between consecutive nucleotides at or near to specific positions within the DNA. They are also called “molecular scissors” because they cut the DNA and produce fragments.
The process of obtaining the foreign gene product from a living source, like a genetically engineered organism (microbial, plant or human cells), is known as bioprocessing.
PCR or polymerase chain reaction is a technique used in molecular biology to create several copies of a certain DNA segment.
Hence, option c is correct.