The correct answer is A.) Chinese immigrants.
Indeed, although the Irish and German immigration waves of the 1850s had also been the subject of hostility due to religious and cultural differences with Anglo-Saxon, Protestant Americans. These were white immigrants that did not constitute a reversal of the racial makeup of the country. Russian immigrants had also faced some hostility and discrimination but the Chinese faced both labor, social and institutional discrimination. In 1882 the Chinese Exclusion Act was passed in order to stop immigration from China for ten years.