The major source of free oxygen in the atmosphere is from .

The difference(s) between the grand canyon and valles marineris is/are: (a) the grand canyon was formed by water, but valles marineris was not. (a) valles marineris is much longer than the grand canyon. (c) valles marineris is much wider than the grand canyon. (d) valles marineris has large volcanoes near it. all of the above

What is most often given a value of zero to describe an object’s position on a straight line? displacement reference point distance ending location

Select the star life cycle that is accurate