Q:

Which of the following events happened first?

• 1
  James D. Watson and Francis Crick wrote Jean K. D. N. The structure of A was discovered
• 2
  Yuri Gagarin became the first cosmonaut
• 3
  Dr. Christian Bernard was the first human heart to be transplanted in the world
• 4
  UK Louie Brown, the world's first test-tube baby, was born in