**Question:** DNA finger printing is done by:

**Core Concept:** DNA Fingerprinting is a technique used in forensic science to analyze and compare DNA samples from crime scenes or suspects. It involves identifying unique patterns of nucleotides in an individual's DNA, which can be used to establish their identity or link them to a crime.

**Why the Correct Answer is Right:** DNA finger printing is primarily done using the polymerase chain reaction (PCR) technique. PCR is a method that amplifies specific regions of DNA to create multiple identical copies, making it easier to analyze and compare the patterns. The correct answer, D, refers to the use of the enzyme restriction endonuclease in the technique. Restriction endonucleases are enzymes that cut DNA at specific sites, allowing scientists to identify unique restriction fragment patterns that are specific to an individual's DNA.

**Why Each Wrong Option is Incorrect:** Option A refers to the process of DNA sequencing, which determines the order of nucleotides in a DNA strand. While sequencing is an important tool in genetics research, it is not used for DNA fingerprinting.

Option B and Option C refer to other molecular biology techniques like Southern blotting and blotting, respectively. These techniques are related to DNA analysis, but they do not specifically identify unique DNA patterns used for DNA fingerprinting.

**Clinical Pearl / High-Yield Fact:** DNA fingerprinting is a crucial tool in forensic science, helping law enforcement agencies to solve crimes, identify missing persons, and establish familial relationships. By analyzing the unique patterns of nucleotides in an individual's DNA, scientists can establish their identity and link them to specific events or individuals.

**Correct Answer:** D (Restriction Endonuclease)