Sentence 3 is the only possible starter for the paragraph as all other sentences have incomplete references within them.
Sentence 2 follows sentence 3 as it explains that there is nothing new about our tendency to record ourselves in pictures and albums as was stated in sentence 3.
The end of sentence 2, “our Facebook for example” links to sentence 1 with its ‘this visual turn in social media…’ and gives us the 3-2-1 sequence.
Sentence 4 then elaborates on the same idea with reference to ‘our friend lists and … with minimal clicks and touches.”’
Sentence 5 then concludes by commenting on ‘what is unprecedented…’ about social media that it has made it easy to broadcast ourselves.
Hence, 32145.