A low coefficient of coincidence indicates that:

A、far fewer double-crossover recombinant progeny were recovered from a testcross than would be expected from the map distances of the genes involved.;
B、crossing over has been enhanced for genes that are located near the centromere of chromosomes because there is less interference of one crossover on the occurrence of a second crossover event.;
C、single-crossover recombinant classes in the progeny have been increased because the genes involved produce lethal phenotypes when in parental gene combinations.;
D、there is a large map distance between one of the outside genes in the heterozygous parent and the middle gene, while there is a short map distance between the middle gene and the other outside gene.;
E、the physical distance between two genes is very short compared with the genetic map distance between these two genes.