Answer:
He played a key role in helping the Russians with peace talks
The best way to measure public opinion is through opinion polls - B
With opinion polls you get an idea what is the general idea about a certain topic from the public, as you usually get a high enough sample to deduce the relevant information.
To answer your second question I would say it is either B or C as being a sole proprietor usually makes you subjec to being a small business or you're forced to use factors of production less efficiently.
"Koine" .... a local Greek dialect used informally in conversation.
The major downfall of the Articles of Confederation was simply weakness. The federal government, under the Articles, was too weak to enforce their laws and therefore had no power. The Continental Congress had borrowed money to fight the Revolutionary War and could not repay their debts.
Hope this helps!