Answer:
source A is used in a school research project.
Step-by-step explanation:
Source A is used in a school research project because it was a book which was written by a university professor after validating from a number of other sources. The data presented is different from one another, the reason behind that may be the historical website missed some other sources. The person who write any historical book, he has a great responsibility to write the correct information so for that reason he take information from the valid sources or writes the information on which most of the historical people agreed. So in that case, source A is a good choice for school project.