If Robert McNamara is one of the options, then he is the correct answer - he was important in the Vietnam War, but not during the WWII.
The united states joined the war and russia dropped out.
Hi,
The Lusitania was sunk in 1915 and the US did not enter the war until almost two years after the sinking. The sinking of the Lusitania and the American reaction to that sinking caused the Germans to temporarily halt their policy of unlimited submarine warfare.
Side note: Found the answer with this link :)
https://www.enotes.com/homework-help/what-impact-did-sinking-lusitania-have-what-came-418703
Answer:Because it connected people and commerce, compressing time and space
Explanation: