The Lost Generation is a term used to describe a group of rebellious American intellectuals, poets,

The Lost Generation is a term used to describe a group of rebellious American intellectuals, poets, artists and writers after the First World War. The main representatives include F. Scott Fitzgerald, John Dos Passos and _______. A. Mark Twain B. Nathaniel Hawthorne C. Ralph Waldo Emerson D. Ernest Hemingway

The correct answer is D. Ernest Hemingway.

The Lost Generation specifically refers to American expatriate writers and artists who came of age during World War I, feeling disillusioned by the war and alienated from post-war American society. Ernest Hemingway is a quintessential figure of this group, alongside F. Scott Fitzgerald and John Dos Passos.

The other authors are from earlier periods:

A. Mark Twain – 19th-century American literature (Realism).

B. Nathaniel Hawthorne – 19th-century American literature (Romanticism).

C. Ralph Waldo Emerson – 19th-century American Transcendentalist.

So, the complete sentence would read:
The main representatives include F. Scott Fitzgerald, John Dos Passos and Ernest Hemingway.