Answer:
The answer is case study.
Explanation:
A case study is a type of research that focuses on a single case. It involves close, direct observation of an event, person or group of people.
The greatest advantage of case studies is that they provide a high level of validty, as the data is gathered through rigorous, in depth analysis, which can be used to predict future phenomena.
They became an independent republic in 1947 so the answer is most likely 1
This letter warned the US that Germany was researching nuclear weapons and it urged the US to research them as well with the hope that the US would finish research on the weapons first. If this letter had not been received by the president, WWII could have turned out completely different than it did.
Encomienda was a social system that started in Spain, where some people, stronger or richer, protected the weaker from outside attacks in return for the weaker people's service (such as in agriculture).