Change sleep to abstract noun

Can someone me answer this english question

Modernist poets were concerned with many issues and used their poetry to express their concerns. which item from this list was not one of their concerns? a.corruption of traditional american values b.brutality of wwi c.the effects of the great depression d.crowded, crime-ridden city life e.alienation of the individual

Think about the noes story. which fits best on the blank line above?