Answer:
The correct answer is option c.
Step-by-step explanation:
The world price of a ton of steel is $650.
During the autarky, the price of steel in Russia was $1,000.
After the trade, the price fell to $650. This means that Russia started importing steel from other countries where it was cheaper. This caused the price of steel in Russia to fall to the level of the world price.
This happens because at price $1,000 consumers will purchase from foreign producers. This will reduce the demand for domestic producers. This decrease in demand will shift the demand curve to the left such that the price falls to $650.