The correct answer is A) An increase in scientific and medical discoveries improved life expectancies.
An increase in scientific and medical discoveries improved life expectancies is the best possible explanation for the changes in Europe's population since 1750.
Life population in Europa changed in the 1750s. The levels of mortality decreased and the levels of fertility increased. Educated people started to design their plan of life, meaning that people became more interested in deciding how many children they wanted to have; this means birth planning. The discovery of effective vaccines, better medicine, and the penicillin, helped to increase and improve the lives of people in Europe.