The first answer is the best answer so pick A
In order to answer this, you must have a clear understanding of the difference between a primary source and a secondary source. A primary source is one that has been written in the time period being studied. A secondary source analyzes key points, often based off of primary sources.
Knowing these definitions, we can conclude that the correct answer is (c)<span> an academic analysis of key battlefield strategies. An academic analysis will provide insight on the topic being studied (in this case battlefield strategies), however it is typically not written with a direct connection to the time.</span>
Answer:
Skin colour, place of birth/origins, culture, ethnicity.