Which was a major justification used by japan for empire building in the 1930s and 1940s?

The correct answer is the lack of minerals and other raw materials as well as food.
Lack of mineral and other natural resources contributed to the rise of post war japan as a major trading nation. Japan's imperialistic leaders also considered it necessary for Japan to engage in trade as a way of obtaining the raw materials it needed. 

The lack of minerals and other raw materials as well as food.

This factor has also shaped post war japan and contributed to its rise into a trading nation. The military leaders who took over power during the decades of imperialism believed that imperialism was necessary to obtain raw materials such as ores and coal for japanese industries.