Answer:
Right choice: B. They detonated a bomb in Japanese territory and blamed China for setting it.
Step-by-step explanation:
In 1931, Japan had already both a strong economic and business presence and a military presence in Manchuria, a region that had been part of China for centuries. It was rich in minerasl and resources needed in industry and with its vastness, it could also offer a solution for the overpopulation of the Japanese islands.
The real motives of the Japanese frame-up was to take full control of the regional resources and consolidate business expansion; Japanese capitals controlled already the South Manchuria Raiwal Company.
So, the Japanese army exploded a bomb on September 18, 1931, and blamed the local government, just a pretext for a full occupation of Manchuria.