In the 19th century, "conservative" and "liberal" were first coming into vogue as terms for political viewpoints. What "conservative" and "liberal" meant then was different from what those terms mean in politics today. 19th century conservatives wanted to conserve and preserve the historic traditions of government and society. For societies like France and elsewhere on the continent of Europe, that meant going back to monarchs in control of government, as things had been before the French Revolution. Liberals were those who favored liberty for individuals, with greater rights and freedoms. So the various answers that spoke of voting rights, elected parliaments, and democratic change -- those all were measures favored by liberals in the 19th century, not conservatives.
Nationalism was a 19th century movement that had the ability to attach itself to either conservative or liberal agendas. In France, feelings of national unity rallied the people to the cause of the French Republic as a liberal form of government. In Russia, on the other hand, nationalistic pride went hand-in-hand with staunchly conservative and autocratic forms of government. In the German states, liberals were the ones who first pushed to form a united German nation. However, it was a more conservative approach under Otto von Bismarck of Prussia that actually accomplished the unification of Germany. So nationalism can be associated with either liberal or conservative causes -- or both.
Conservatism: the ideology to commit to and promote traditional values. It's also the holding of socially conservative ideas. Conservative folks are more likely to oppose change or innovation.
Liberalism: an ideology that's quite the opposite of conservatism; one of the basic tenants of liberalism is tolerance. This philosophy is more focused on liberty and equality, so liberal folks are more likely to welcome change.
Nationalism: an extreme form of patriotism. Nationalists are all about superiority, feeling superior than any other person or any other country. These people typically promote their interests to a particular nation.
One way in which Americans developed a unique cultural identity after the Revolution was by ratifying the Constitution, which created a true "nation" as opposed to a lose confederation of states, which allowed people to develop a sense of nationalism and "pride" in their country.
