How has the united nations changed the world

Perspective and influence. Without the US, many countries wouldn't be where they are today. To them, the US is a country where there is an opportunity in every corner, slavery is abolished, and a place to escape from persecution. Without the US, lots of immigrants would still be suffering in their home country today. 

They changed the world while not doing jack squat during the Rwandan genocide. They sat there and did nothing because they didnt want to get there hands dirty

The answer b is correct this all occurred during the red scare