The answer is d, strata formation. because the earth's ground, even under water, is always shifting, after some time, rock formations can occur. it can sink, create sink holes, crack apart, and residual rock & earth can form new strata.
I believe its the Rhine-Main-Danube Canal. Hope that helps!
depends on how algebraically equations its different types ways how you solve equations
Often, waterfalls form as streams flow from soft rock to hard rock. This happens both laterally (as a stream flows across the earth) and vertically (as the stream drops in a waterfall). In both cases, the soft rock erodes, leaving a hard ledge over which the stream falls