The correct option will be (C) they are flooded by the rising sea levels.
Explanation:
We know that the European coastal regions come across the rise in the sea level. The sea level is rising due to green house gases which leads to global warming . As a result all the glaciers are melting and thus resulting in the rise of sea level. When the sea level rise the agricultural area of the Northern region of Eastern Europe gets affected. As a result the farmers of the northern regions of the Eastern Europe face problems.Thus the production of crops decreases.