Which poet is associated with the Modernist movement and renounced American citizenship?

T. S. Eliot is a key figure in the Modernist movement, known for his innovative use of language and form in poetry that responded to the complexities of the 20th century. His works, such as "The Waste Land" and "The Love Song of J. Alfred Prufrock," exemplify the fragmentation and the exploration of new aesthetics that characterize Modernist literature.

Eliot's renunciation of American citizenship is significant in understanding his identity and literary perspective. After moving to Europe and settling in England, he became part of the literary scene there, deeply engaging with the cultural and intellectual developments of Europe, which greatly influenced his work. This transition reflects the broader themes of displacement and identity that are prevalent in Modernist poetry.

The other poets listed, such as Robert Frost, Walt Whitman, and Emily Dickinson, while all significant figures in American poetry, did not renounce their American citizenship or share the same profound connection to the Modernist movement. Frost, for instance, often celebrated New England themes, while Whitman and Dickinson are more closely associated with earlier American literary traditions.