When Bradshaw and colleagues investigated the quantitative trait loci (QTL)of two species of Mimulus (Mimulus cardinalis and Mimulus lewisii),they used marker loci as a way to map the QTLs.Their results are shown in the accompanying figure.According to these results,________.

A) the differences in genotype for the majority of these QTLs explained small amounts of the variations in flower phenotypes for both species
B) some of the QTLs did have pronounced effects on the flowers' phenotypes
C) at least one QTL explained 90% of the phenotypic variance for each species
D) All of the above.