The organization of petroleum exporting
countries (opec) was formed with the intent of
(1) stabilizing the supply of oil to japan
(2) cutting off the supply of oil to the united
states and its allies
(3) increasing the supply of oil available for use
within middle eastern countries
(4) controlling the supply of oil to raise prices

no options provided, here,but the answer to this question is often: a historian cites a japanese newspaper article published a year after the end of world war ii in order to draw conclusions about the effect of the war on the japanese economy.

clearly from the answer, the historian alludes to historical sources,and records to aid in analyzing and drawing conclusion on the effect of the war on the economy of japan.