What important characteristics unique to land plants are thought to be critical evolutionary advances that contributed to their success on land?

the answer is z.

the human body has five levels of organization. level 1: cells. cells are the basic units of life and form the first level of organization. cells in the human body have specific functions. examples include nerve cells, blood cells, liver cells, and so on.

for a different answer set the answer would be because the oxygen in the water had depleted (apex)