Which geographic feature made trade in China more difficult? river systems, mountain ranges, lowland grasses, desert oases

What was the main purpose of one of the first world organizations

What statement about risks in social and behavioral sciences research is most accurate: anonymizing data effectively manages the risk of creating emotional distress.risks are specific to time, situation, and culture.there are never any risks.if a study offers potential benefits, it is not necessary to minimize risks.

The principle that the geoglical processes that we see today have occurred through out earths history is called