Solution
The paragraph discusses how the internet enabled global connections and transformed communication. The blank needs to bridge the idea of "worldwide connections" to the subsequent metaphor of the "backyard fence" being replaced by a computer monitor.
Option 1 is a specific historical detail about social media, not the general communication shift.
Option 2 contradicts the entire premise that the internet brought significant change.
Option 3 focuses on social media, while the preceding sentence discusses the internet's broader impact on worldwide connections and the subsequent sentence talks about general communication.
Option 4 accurately encapsulates the fundamental shift in scale and reach of human interaction enabled by the internet, perfectly setting up the metaphor of the backyard fence being replaced by a global connection, thus providing the best logical flow.