The phrases “O Blues!” and “Sweet Blues!” are examples of

Repetition.

Explanation:

Langston Hughes' poem "The Weary Blues" talks about the power of man's art, especially black artists. The poem talks of the resilience and perseverance of the common man at times of adversaries and problems.

In the given lines from the poem, the author exclaims, "O Blues!" and "Sweet Blues" referring to the blues genre of music. These two lines are an example of repetition. The repetition can be found in the words "blues" which is used in successively.

Thus, the correct answer is repetition.

vector v such that t( p) = p+ v

a.) literature that explores grotesque characters and eerie, violent occurrences in a dreary setting.