The correct option is
B a−3,b−4,c−1,d−2Heat shock - Bacterial cell
Heat shock method is one of the most common methods of making bacterial competent cells. This method involves the following steps:
- Bacterial cells are treated with divalent ions (Ca2+) followed by a brief heat shock.
- Heat shock is provided for a brief time period which creates transient pores within the bacterial cell membrane.
- These pores allow the DNA of interest to enter into the bacteria.
- These cells are placed back on ice to retain the plasmids inside the bacteria.
Biolistics - Plant cell
Biolistic or gene gun is a method of transfer of genes in cells. In this technique, gold particles are coated with nucleic acids such as DNA and bombarded into cells at very high speed.
It is the most widely used method to deliver foeign DNA in plant cells because of the presence of an additional membrane and cell wall in plants.
Selectable marker - Antibiotic resistance gene
Selectable marker is a gene in a vector that helps in the selection of transformants (host cells which have successfully taken up the foreign DNA) and non-transformants (cells which have not taken up the vector DNA).
For example, antibiotic resistance genes in the vector act as selectable markers because they confer antibiotic resistance to the transformants while the non-transformants remain susceptible to antibiotics.
Micro-injection - animal cell
Micro-injection is one of the methods of DNA delivery in the host cell. This method is used to inject recombinant DNA directly into the nucleus of an animal cell with the help of a microinjector.
Hence the correct option is
c.
a−3,b−4,c−1,d−2