In Humans,which Genetic Mechanism Led to the Formation of the X

Question

In humans,which genetic mechanism led to the formation of the X and Y chromosomes?  
A) Translocation
B) Nondisjunction
C) Inversion
D) Reduced crossing over
E) Insertion

Accepted Answer

Reduced crossing over between the X and Y chromosomes over evolutionary time has led to their differentiation and the formation of distinct sex chromosomes. This limited recombination allowed for the divergence in size and gene content between the X and Y chromosomes.