Hair is a potential evidence which can be used to establish the linkage to the culprit or victim it belongs to by the DNA analysis of hair. For establishing the similarity about 10% cannot be matched this is due to some experimental errors as wells as quantity and quality of the hair strands that are to be compared.
Since DNA analysis take a huge amount of money , the FBI only test the suspect whom they almost 100% sure is the suspect.
But according to researches, about 10 % of the 'matches' in the physical characteristic of hairs were contradicted by the DNA analysis
answer; i believe that the correct answer is (light);