The "iron curtain" Winston Churchill referred to

The iron curtain was a metaphorical separation between the West, and Russia.

Explanation:

Following WW2, the Western powers and Russia had differences in ideology pertaining to the economic system to be used for development. Russia favored communism, while the western powers favored capitalism. Winston Churchill used the term "iron-curtain" to allude to the separation between ideologies in the European hemisphere. It wasn't until the development of the Berlin wall that there was a non-metaphorical/physical separation between the ideologies.

a. theta waves. this is because the person is in a light sleep which means the brain waves would show these kind of waves.

number 4. should be the correct answer