Question

A historian wants to better understand the causes and historical context of Iraq's invasion of Kuwait. What source would be most helpful for him?

Answer 1

Assuming that this is referring to the same list of options that was posted before with this question, the correct response would be the transcripts of deliberations between the Americans in the war room leading up to the invasion, although these are classified. 
A recorded conversation between Iraq's generals the day before the invasion

Answer 2

I think the best source that would be best helpful for this historian is the transcripts of the Americans in a meeting which leads to the invasion. With this source, the historian can clearly hear what really happened and he can understand the causes.