b) Japan

The Gentleman’s Agreement of 1907 was a significant but informal agreement between the United States and Japan. Aimed at reducing tensions over immigration, it resulted in Japan agreeing to restrict the emigration of its citizens to the U.S., while the U.S. refrained from imposing formal restrictions on Japanese immigrants. This agreement was a response to anti-Japanese sentiment on the West Coast and represented an early example of U.S. immigration control based on national origin.