DNA evidence helps identify crime suspects but falls short of being perfectly conclusive due to multiple reliability issues. The correct answer to the multiple-choice question is d. all of the above, as each option represents a real forensic challenge.​

Option Analysis

Degradation occurs when environmental factors like heat, moisture, or time break down DNA samples, fragmenting them and hindering analysis, especially with older methods like RFLP. Contamination happens through accidental transfer of other individuals’ DNA from investigators, victims, or scenes, often due to poor PPE use or scene access control, which modern sensitive PCR techniques amplify. Insufficient data arises in mixtures from multiple people or low-quantity “touch DNA,” preventing unique individual matches, as seen in complex cases like sexual assaults.​