The open door policy was challenged by what country with its invasion of manchuria in the 1930s? a. japan b. korea c. philippines d. russia

Correct  a. Japan

History/context:

In 1931, Japan invaded and occupied Manchuria, the northeaster region of China.  The invasion followed an explosion that blew up a portion of railroad tracks near the city of Mukden.  (Thus it became known as "The Mukden Incident.")  The railway was owned by the Japanese, who had invested in development in the region, taking advantage of China's open door policy.  Japan blamed Chinese nationalists for the explosion, but others thought the bombing may have been done by Japanese military personnel to provide Japan with an excuse for invading and occupying Manchurian territory.  The Japanese declared the region to be a new country, independent of China. which the Japanese called Manchuko.  In reality, the territory was not independent but was controlled by the occupying Japanese army.

The League of Nations condemned Japan in 1933 for the events in Manchuria, but that did little to stop Japan.  Japan withdrew from the League of Nations at that time, and by 1937 began further invasions into Chinese territory. and in the early 1940s Japan occupied French Indochina (territory in Southeast Asia).

b) the importance and limits of political power.

c) troops march forward in close formation against newer, more accurate weapons