The most accurate conclusion about the change in gender structures in early India from the early Vedic Period to the late Vedic Period is:
d. Women lost all rights and became second-class citizens.
While there were variations in women's roles and statuses during these periods, the late Vedic Period saw a decline in women's rights and status, with more restrictive norms emerging, including limitations on their social participation and rights. This transition marked a movement towards a more patriarchal society, in which women were often relegated to a subordinate status.