I'm sure it's B. Or D. I would go with B.
The U-2 incident was over a US CIA spy plane flying over the Soviet Union and taking photos of military installations and it was shot down by a missile from the Soviet Union so it caused a serious rift in relations between the two superpowers.
Answer
not very sure because im dumb but i would assume
people are used to buying candy for their children sorry if im wrong :)
Explanation: