Why do boundaries cause problems

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

Pythagorean theorem what is the value of x? x = 2 sides are 8 and 10

How do the absence of sunspots affect earth climate