Free verse: poetry that does not use a consistent rhyme scheme
iambic pentameter: a poetic rhyme scheme in which each rhyming line has ten syllables
blank verse: poetry that uses unrhymed iambic pentameter
rhyming couplets: a series of two consecutive lines that rhyme in a poem

based on the descriptions, what rhyme scheme does the poem "harlem" use?
free verse
iambic pentameter
blank verse
couplets

A). Free Verse.

Explanation:

Free Verse is illustrated as the literary device in which the author is free from the restrictions of the regularity of structure or form, meter, or rhyme scheme. Such literary form assist the authors with the essential artistic liberty to express their thoughts in their art more naturally and emphatically.

As per the question, 'free verse' is the rhyme scheme that has been employed here in this poem 'Harlem' as it does not employ a consistent rhyme scheme and each line is structured in a specific pattern and uses different literary devices(simile and metaphor) that gives a special effect to it. Thus, option A is the correct answer.