The détente eased tensions between both. The détente was agreed upon by both U.S and the communists to control their weapons of power to secure safety. It later ended the Cold War that was occurring between the two limiting the threat level of both sides.
Transportation, commerce, to get from A to B. Where rivers were not proper for transport, the rail was the best option that time.
They were afraid of large numbers of Jews coming in from (in the case of the St. Louis) Germany. 900 people is a lot of people but it would only be the tip of the iceberg if people were allowed to cross the Atlantic and go into the United States. There was a quota of how many people could come in and the US wanted to keep to the quota system.
The United States (at the time of the St. Louis sailing) was neutral, so they also didn't want to endanger that neutrality.
I would say A because Tsar Ivan III changed Moscow to an Eastern branch of Christianity or Orthodox Church and considered it "Third Rome" also he was in total control and Tsar's were the equivalent of King's in modern time.
1. Stop the formation of trusts
2. Prevent big businesses from purchasing competitors
3. Create laws against monopolies
