A historian might use periodization in order to separate the different cultural and political movements in Ancient Greece. It's a good way to categorize and organize the vast history of Ancient Greece, in order to make it more easily understandable. It's also a good way to examine differences in ideals and culture shifts across time.
I think the statement that describes the cause of the Cuban Missile Crisis is letter D. The Soviet Union set up missiles in Cuba and aimed them at the United States. I hope you are satisfied with my answer and feel free to ask for more if you have more clariffications
