Biolistics (gene gun) is suitable for:

The correct answer is Option (1) → Introducing rDNA into plant cells

Option (1) Introducing rDNA into plant cells — Correct. In biolistics (the gene gun) cells are hit with high-speed gold or tungsten particles coated with DNA. It is suited to plant cells, whose thick cell walls make other methods hard.

Option (2) Introducing rDNA into animal cells — Incorrect. Recombinant DNA is introduced into animal cells mainly by micro-injection directly into the nucleus. Biolistics is the method suited to plant cells.

Option (3) Disarming the pathogen vectors — Incorrect. Pathogens are disarmed by removing their disease-causing genes, as in the Ti plasmid of Agrobacterium. The gene gun only shoots DNA-coated particles into cells; it does not disarm anything.

Option (4) DNA fingerprinting — Incorrect. DNA fingerprinting compares repetitive DNA (VNTRs) between people by Southern blotting. The gene gun is a method of introducing DNA into plant cells, not a way of identifying DNA.

NCERT Extract:
Cloning Vectors – “… Recombinant DNA can then be forced into such cells by incubating the cells with recombinant DNA on ice, followed by placing them briefly at 420C (heat shock), and then putting them back on ice. This enables the bacteria to take up the recombinant DNA. This is not the only way to introduce alien DNA into host cells. In a method known as micro-injection, recombinant DNA is directly injected into the nucleus of an animal cell. In another method, suitable for plants, cells are bombarded with high velocity micro-particles of gold or tungsten coated with DNA in a method known as biolistics or gene gun.”