D

 These are kits that contain three basic materials: primers, reaction mix and polymerase. The kits also contain the fluorescent tags that allow the amplified DNA fragments to be detected during the electrophoresis phase. The reaction mix is a combination of chemicals used in any form of PCR testing that, in essence, creates the proper chemical environment for the PCR process to occur. The reaction mix is not locus-specific. The polymerase is a class of enzymes that enable bases to be added to the primer. It too, is not locus-specific.

The elements of the kits that are locus-specific are the primers. The primers ...