Question

Which research source is an example of a primary source?

a movie about Cold War–era chess
a textbook chapter about the Cold War
an article about the Cold War by an expert
a photograph taken during the Cold War era

Answer 1

A photograph taken during the Cold War era.

It's a primary source because it’s an original, contemporaneous record from the time. The others are secondary (textbook chapter, expert article) or likely secondary (a movie about the era) unless they were created at the time as firsthand material.