While researching a thesis paper on ronald reagan’s presidency you discover multiple resources that support your argument. which resource would be the most valid and reliable

The correct answer is:

a. A newspaper reporter who covered the Reagan presidency.

I believe a newspaper would be the most reliable source of information, because newspaper reporters tend to be subjected to higher standard of journalism. Even though it's true that bias would still exist depending on the journalist who wrote the coverages, they are the most trusted sources compared to other people in the options above.

the term is einsatzgruppen

i believe it was spain