The Excuse Used by Japan for Provoking the Manchurian Incident

The excuse used by Japan for provoking the Manchurian Incident in 1931 was

A) a riot by the Chinese against a Japanese ambassador.
B) the need to declare a war on drugs against China's opium trade.
C) an explosion on a railway track.
D) that the Chinese were allying with Russia, and Japan wanted to prevent a recurrence of the Russo-Japanese War in 1905.
E) that China threatened Japanese imperial holdings in Korea.