Answer: D. The relationship between the United States & Russia
Step-by-step explanation:
The cartoons are related together in their depiction of the relationship between Russia and the U.S in 1956 and 2018. In 1956, tensions with Russia (then the "Soviet Union") and the United States were very high with the Soviet Premier, Nikita Khrushchev, threatening the security of the United States.
This, according to the cartoon, is a sharp contrast to the relationship between Russia and the U.S. in 2018 with the "good" relationship that President Donald Trump seemed to have with the Russian President, Vladimir Putin.