DNA fingerprinting works on the principle of

The correct answer is Option (2) → Polymorphism in DNA sequences

Option (1) Dimorphism in DNA sequences — Incorrect. Dimorphism means only two forms. DNA fingerprinting uses many variants in repetitive DNA from person to person, which is polymorphism.

Option (2) Polymorphism in DNA sequences — Correct. DNA fingerprinting compares the DNA of individuals at regions that differ from person to person. It works on the principle of polymorphism in DNA sequences, using repetitive DNA such as VNTRs whose copy number varies between individuals.

Option (3) Dimorphism in RNA sequences — Incorrect. DNA fingerprinting compares DNA, not RNA, and the variation it uses is polymorphism, with many forms, not dimorphism.

Option (4) Polymorphism in RNA sequences — Incorrect. The variation used is polymorphism, but in DNA, not RNA. DNA fingerprinting compares repetitive DNA sequences such as VNTRs.

NCERT Extract:
DNA Fingerprinting – “… As polymorphism in DNA sequence is the basis of genetic mapping of human genome as well as of DNA fingerprinting, it is essential that we understand what DNA polymorphism means in simple terms. Polymorphism (variation at genetic level) arises due to mutations. (Recall different kind of mutations and their effects that you have already studied in Chapter 4, and in the preceding sections in this chapter.)”