What does contribute to the article mean?

The opening stanza portray a frightened narrator fleeing though darkness. how does it rhythm reflect and enhance its meaning

The great depression, which lasted throughout the 1930s in the united states, affected many people, and it had a devastating impact on an entire subset of the u.s. population. modernist writer john steinbeck wrote about the toll the depression took on these families, many of whom were forced to leave their farms and find other sources of income.

Which of the following pronouns are singular