Arrange the following events in an ascending chronological order with the help of given code:i. U2 incidentii. Helsinki Conference on Security and Co-operation in Europe.iii. Nikita Khrushchev ousted from Soviet Leadershipiv. Nuclear Test Ban Treaty signedCodes:

• A. ii i iii iv
• B. i iv iii ii
• C. iv ii i iii
• D. iii iv ii i