Which research topic has the narrowest scope?

- the Civil Rights movement

- Martin Luther King's "I Have a Dream" speech

- Bob Dylan's choice of words in "The Lonesome Death of Hattie Carroll"

- segregation

The topic with the narrowest scope might be 'Bob Dylan's choice of words in "The Lonesome Death of Hattie Carroll"'. The three other topics talk about events that can be interpreted in a myriad of ways but the lyrics of the song are more straightforward.