Final answer:
Emily Dickinson led a revolution in poetry, challenging traditional poetic form, language, and themes, and her work represents a significant departure from the American literary tradition.
Step-by-step explanation:
The author who led a revolution in poetry, pushing aside generations of assumptions about proper style, words, and subject matter, particularly in the context of the choices provided, is Emily Dickinson. Dickinson's innovative and unconventional use of form and syntax, along with her thematic explorations of death, nature, love, and the metaphysical, signaled a break from the American literary tradition of her time.
While Walt Whitman is also known for his groundbreaking free verse and inclusive themes, which reshaped American poetry, the question specifically mentions the 'revolution poetry' about proper style and subject matter, which is more closely associated with Dickinson's work. On the other hand, Langston Hughes was a leading figure of the Harlem Renaissance and T.S. Eliot was a pioneer of modernist poetry. However, when it comes to fundamentally challenging the prevailing traditions of poetry through individual expression and a shift in thematic content, Emily Dickinson stands out among the options given.