Which transcendentalist wrote 'Walden' and is known for his act of civil disobedience regarding the Mexican War?

The correct choice is Henry David Thoreau, who is renowned for his book 'Walden,' in which he reflects on simple living in natural surroundings and explores themes of self-sufficiency and individuality. Thoreau is also significant for his practice of civil disobedience, particularly in his essay "Civil Disobedience," where he argues against government policies like the Mexican-American War, which he viewed as unjust. His refusal to pay a poll tax as an act of protest against the war exemplified his belief in following one's conscience rather than obeying laws that one finds morally objectionable. Thoreau's ideas contributed to the philosophical underpinnings of later movements advocating for social justice and individual rights.