In Humans and Other Mammals, X-Inactivation Takes Place

In humans and other mammals, X-inactivation takes place:

A) early in development, with each new cell inheriting the same inactivated X chromosome as its parent cell.
B) late in development, with each new cell inheriting the same inactivated X chromosome as its parent cell.
C) throughout the lifetime of an organism-with each new cell division, both X chromosomes are activated, and one is then inactivated in each new cell.
D) early in development, with all maternal X chromosomes being inactivated and cells maintaining active copies of only the paternal X chromosome.
E) early in development, with all paternal X chromosomes being inactivated and cells maintaining active copies of only the maternal X chromosome.