World war II ended in 1945, it looks like there was a large decline right after in 1946. The cold war began in 1947 until 1991, which is not seen on the graph. But yes, I would say C is the best answer.
A, cant be proven with this graph.
B Nothing about the soviet union on this graph. (unless there is another graph about the soviet union on your quiz?)
D, Wrong because it was at its lowest in 1946 not its highest
