The VNTR alleles analyzed in forensic DNA fingerprinting experiments are highly variable from individual to individual. How do the many VNTR alleles at a single locus differ from each other?
A. the number of internal restriction endonuclease cleavage sites for the enzyme HaeIII
B. the number of protein coding genes
C. the number of DNA methylation sites
D. the number of times a simple DNA sequence is repeated
E. NONE of these