Answer:
The resolution of agarose gel.
Explanation:
The resolution of a common agarose gel is not high enough to be able to differentiate the genetic differences (polymorphisms) that can produce the VNTR gene, located at the D1S80 locus. The VNTR fragment produces variants between 10-50pb, which means that a highly trained eye and a very good quality agarose will be required to differentiate a homozygous from a heterozygous individual.
