This is NOT a test or any graded assignment, I'm reviewing right now on my SAQ skills and I need some help with it, what are some key points which you guys would bring up for these questions?

Iwould say a, due to the fact these routes display many things that would be useful and provide explanations for how states are known.

Primary sources are usually  more accurate and are written by someone who experienced it or witnessed it. secondary sources are those who heard of it after the fact that can lose details and or twist the event in a light that benefits them.