Answer: Option D " all of the above "
Explanation: DNA can be a great source of information when used as a forensic evidence. This technique has many advantages and disadvantages when used as a source of information in case of crime.
Identical twins: There are some common fragments of DNA that is same in identical twins so it can be a difficulty in deciding the criminal.
Not enough of a sample: DNA should be present in a detectable amount to be used an sample for evidence, less than this detectable amount is a waste and cannot be used as a sample for evidence.
Contaminated and degraded sample: If the sample of DNA is contaminated or degraded then the result might be incorrect and might not be used as a sample for forensic evidence.
Hence, the correct answers are all of the above.