Answer:
A. Symbolized the Cold War.
Explanation:
Considering the available options, the choice that contains a sentence fragment is "Symbolized the Cold War."
This is because "Symbolized the Cold War, " does not form a complete sentence, but rather just a part of it. The phrase makes the reader wonder what "symbolized the cold war." Hence to have a complete sentence there is a need to be an independent clause attached to it or the necessary components.