Which idea of Henry David Thoreau was adopted by twentieth-century leaders of great social change movements? A. individualism. B. inner light. C. different drummer theory. D. civil disobedience.

The idea of Henry David Thoreau that was adopted by twentieth-century leaders of great social change movements is D. civil disobedience. Thoreau's essay on civil disobedience advocated for the individual's right to resist unjust laws and government actions, influencing many prominent figures such as Martin Luther King Jr. and Mahatma Gandhi in their respective movements for social justice and civil rights.