Answer:
A. The divide between Eastern and Western Europe.
Step-by-step explanation:
The term "Iron Curtain" refers to the imaginary and invisible boundary line that divides Europe based on political, ideological as well as military beliefs. This barrier is not a literal/ physical barrier like the Berlin wall, for it is just a "thought process" barrier of the Soviet Union.
This imaginary barrier was developed to prevent any form of influence from the western side of Europe. Soviet Union tried to prevent any influence from its western counterpart after World War II, preventing any form of contact between the two. This concept of the Iron Curtain was to make sure the Eastern side remains devoted to the Soviet's belief and not become like the western side.
Thus, the correct answer is option A.