Final answer:
Nuclear DNA is the form of evidence that conclusively establishes positive identification. It involves analyzing DNA sequences from samples and comparing them with known individuals to match identities, widely used in forensic science for criminal investigations and other legal cases.
Step-by-step explanation:
The type of evidence that establishes positive (not presumptive) identification is b. Nuclear DNA. Nuclear DNA analysis involves sequencing and analyzing DNA from an unknown sample and then matching it with DNA from a known individual. This process can confirm relationships, such as paternity, as well as provide conclusive identification in forensic cases. For instance, DNA extracted from samples like blood or skin cells can be matched precisely to a suspect's DNA. DNA analysis has also been instrumental in immigration cases, as demonstrated by the teenage boy who was proven to be the son of his mother through DNA analysis.
Forensic scientists utilize DNA by extracting it from biological samples such as hair, blood, or saliva. The unique DNA sequence is then amplified, often using polymerase chain reaction (PCR), to generate a sufficient quantity for analysis. Afterward, these sequences are compared with those in a database or with known samples to establish identity. This DNA fingerprinting is critical in criminal investigations and has become a cornerstone of modern forensic science.
DNA analysis can be used to compare samples from an unknown source with DNA samples from a known individual, such as a suspect in a criminal investigation. By comparing the DNA profiles, forensic scientists can determine if there is a match, providing strong evidence of positive identification.