Answer:
because they produced most of what they needed .
Its D for sure i was stuck on this one
The answer would be : D. Russian adaptation to extreme cold
If a steel is exposed to an extreme low temperature over prolonged period of time, the structural form of the steal could be damaged, which could lead to a destruction of a building's foundation. In order to prevent this, a country which extreme winter such as Russia developed a special steel that won't crack.
