Answer:
Correct answer is Both lowered the population of Europe.
Explanation:
First option is correct is because Black death and famine that often happened in 14th Century reduced the population of Europe according to some estimates between 40 and 60 percent.
Second option is not correct as only famine was caused by the climate and weather changes.
Third option is not correct as black plague didn't affect this, as the famine did.
Fourth is also wrong, because unrest came later, after this events.
