<span>An increase in scientific and medical discoveries improved life expectancies.
</span>The best possible explanation for the changes in Europe's population since 1750 is that an increase in scientific and medical discoveries improved life expectancies.In fact, it was around this type that basic hygiene norms were implemented, as well as some mortal diseases were cured or to improve lifbetter treated. Moreover, the discovery of vaccinations helped greatly to improve life expectancies.
The WPB or War Production Board set the products that would be needed for war and they determined their pricing.
So I agree with you, the answer is A.
But I must admit I was a bit iffy between A and D but I'd still say that A is a better choice.
Hope this helped
The answer is c. amendments to the Constitution that would strengthen New England's political power