The correct answer is the following: option c. Thoreau believes that a government based on a majority rule cannot be based on justice because they determine what is right based on the strength in their numbers rather than the conscience.
Thoreau main idea is that "the government is best which governs least". Indeed he said that one day men would be able to have a government that does not govern at all. He also argues that democracies, by answering to majorities, are answering to the strongest group, not the most thoughtful, therefore that type of government cannot be based on justice, as not because the government is the strongest group does that means that it possesses more consciousness than the rest of the citizens.
option c. Thoreau believes that a government based on a majority rule cannot be based on justice because they determine what is right based on the strength in their numbers rather than the conscience.