An accurate identification of a rapist can be carried out by conducting

Analyze the question: The question asks which method gives an accurate identification of a rapist. The key word is "accurate", so we need the test that is unique to each individual.

Explain the concept:

• DNA analysis (DNA fingerprinting/profiling): Every person's DNA is unique, except identical twins. Biological evidence left at a crime scene, such as semen, blood, hair or skin cells, contains DNA. This can be compared with a suspect's DNA, and the match is extremely reliable.
• RNA analysis: RNA is unstable and breaks down quickly. It varies with which genes are active in a cell, so it is not used for identifying individuals.
• Blood group test: Many people share the same blood group (A, B, AB, O). It can only rule out suspects, not positively identify one.
• Behavioural tests: These are subjective and unreliable. Behaviour can be faked or misread, so they cannot prove identity.

Solution:

1. Identification needs a feature unique to one individual.
2. Only DNA is unique and stable enough to be recovered from small biological samples.
3. Blood group is shared by millions, RNA is unstable, and behaviour is subjective.
4. Therefore DNA analysis is the most accurate method.

Answer: B. DNA analysis

Exam tip: When you see "accurate identification", "paternity", "crime scene" or "forensic" in a biology question, think DNA fingerprinting. A quick way to remember it: DNA = Definitely Naming the Accused.