Although the vast majority of women who inherit a single copy of an x-linked recessive disease allele are not affected by the disorder, a small percentage of women do display the disease phenotype. which of the following could explain this rare phenomenon?

a. x-inactivation that favors inactivation of the normal x chromosome
b. incomplete penetrance of the x-linked recessive allele
c. turner syndrome (a sex-chromosome aneuploidy in which women have only one x chromosome)
d. multiple alleles of the x-linked recessive trait