The right answer would be D. taxes.
Henry Thoreau advocates that when you find that your government is using your tax money to finance something unjust (in his case, the Mexican-American war) or is prolonging an unjust situation (such as the slavery), the more just thing to do is to stop paying taxes, in protest, and face the legal consequences.
He states that if every person who is against war or slavery stopped paying his taxes eventually would bring a change on the laws, inciting the politicians on passing laws that favored they way of thinking.
