How do geologists determine the location of plate boundaries?

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 are the answers for the following questions?

Which of the following is the main purpose of using an anchored network of booms which funnel debris to a collection area?