Triple x syndrome, or trisomy x, occurs when a female has an extra x chromosome in each of her cells. this results when the mother's reproductive cells divide improperly, and two x chromosome are moved into one gamete. when that gamete is fertilized and the father's dna and x chromosome are combined with the mother's, that gives the cell three x chromosomes instead of two. triple x syndrome occurs because
a) crossing over
b) nondisjunctions
c) point mutations
d) deletions