What does this question mean? How Can I better understand DBQ questions?

Test Preparation AP Test Preparation
1

I’m unable to understand what this question:
Using the documents, compare and contrast the attitudes of Christianity and Islam toward merchants and trade from the religions’ origins until about 1500. Are there indications of change over time in either case, or both? What kinds of additional documents would you need to asses the consequences of these attitudes on merchant activities?

Means, I know its asking for the attitudes but what does it mean when it says what kinds of additional documents would you need…
Does this mean I have to use outside evidence or what?

2

Here’s a helpful link.
https://slideplayer.com/slide/11963007/
BTW the WHAP exam does say you can use outside knowledge not mentioned in the documents.