Hey there! I'm happy to help!
Let's look for answers that have to do with technology.
Smaller nations becoming part of larger empires is not really related to new technology, so this answer is not right.
Technology would not have allowed a smaller number of refugees during the war because the main thing that would have allowed a smaller number is more peaceful countries and places to take refuge, not necessarily new technology.
A slowdown in transportation improvements does not make much sense because if technology was improving it should have been easier to improve this.
New technology could have allowed for more military casualties because new and more destructive weapons such as machine guns, flamethrowers, tanks, etc. that would have caused many more people to perish.
Therefore, the answer is 3) increased military causalities in battles fought during the war.
Have a wonderful day!
