Reading the jumbled sequence, we can easily identify the starting sentence. Sentence 1 starts the sequence by introducing the topic ‘Our knowledge about life developed over centuries…’
2 follows 1 as it refers to ‘this long history’ and a year (1953) that has been taken out of this long history.
3 follows this as it continues with its reference to ‘in that year’ ( 1953)
And 4 completes the sequence by expanding on the experiment mentioned in 3.
Hence 1, 2, 3, 4 is the correct sequence, and A is the correct answer.