The correct option is B IV only
Polymerase Chain Reaction (PCR) is an indispensable tool in modern molecular biology and diagnostic techniques. PCR is a reaction in which amplification of a specific DNA sequence is carried out in vitro to generate millions of copies of the DNA. It aids in diagnosis of various diseases, like HIV and genetically inherited diseases.
The PCR method is useful in situations in which the amount of DNA is limited, such as forensics and parental testing or in which the quality of the DNA sample is poor. PCR is extensively used in forensic labs to identify criminals by collecting any sample of blood, hair etc. It amplifies the available DNA sample for futher DNA fingerprinting to match the genetic information with the person it came from, which makes it possible to identify any person from millions of others.
PCR is used to detect and characterise microbial pathogens and characterise mutations associated with carcinogenesis. PCR is performed to characterise and identify the transgene in an individual by amplifying the gene of interest or target DNA.
DNA sequencing is a technique of determining the exact location of the nucleotide bases (A, T, G and C) in a DNA molecule. PCR does not sequence the DNA, but amplifies it in multiple copies. There are other molecular techniques used to deduce the sequence information like - Sanger sequencing, next-generation sequencing etc.