The correct answer is D. Kokura was designated as the secondary, back up option for the nuclear bomb named “Little Boy” that was dropped on Hiroshima. For the “Fat Man” bomb, Kokura was a primary target. It was spared from the destruction by the poor weather conditions as it was shrouded by heavy smog and clouds so the US command changed the bombing target to be Nagasaki.
You are wrong, Its B.to demonstrate that Kokura was the original target city for the second bomb,