Final answer:
The primary source document about the Cold War is Winston Churchill's “Iron Curtain” speech, as it is a first-hand account from a key figure at the time.
Step-by-step explanation:
A primary source document about the Cold War would be an original document or evidence from the time period in question. Considering the options provided, Winston Churchill’s “Iron Curtain” speech is the correct answer. Churchill's speech, delivered in 1946, articulated the division of Europe and the ideological conflict between the democratic nations and the Communist nations. This speech is a first-hand account from a key figure directly involved in the historical context of the Cold War and as such is considered a primary source. Options A, B, and C represent secondary sources, providing analysis or commentary on primary sources or historical events, and option D, while being an authentic piece of history, does not contain content about the Cold War itself.