Answer:
B. Natural gas
Step-by-step explanation:
Natural gas is one of the main natural resources found in Eastern Europe. It is mostly found in Russia, Ukraine, Romania, Albania, and Hungary.
Even during the time of the Soviet Union, Soviet gas was one of the main good imports on the Western European market. In Siberia, gas development happened during the 70s and 80s. Today, Russia is the second in the world when it comes to the production of natural gas and they provide one-quarter of all the gas for the EU.
Sadly, the gas consumption is growing and the supplies are running out – there is a fair chance that Europe will run out of natural gas resources in near future.