Me (30 points) + brainliset answer

Hmm, let's see:
The title doesn't really make any sense because,
we are probably going to be needing a specific information
about the civil war, and there is a lot of different subtitles to talk from there,
so I'm pretty sure it's not that one. 
The first and last sentence probably won't work either because,
you will need a lot of more research than from just 2 sentences.
Bold words can be helpful in a way but, that wouldn't be the answer because, bold words help you understand difficult words/phrases. Index would certainly be the answer because, instead of flipping through all the pages, you can just go to the index and find the topic you are looking for, (In the index, the different topics discussed in the book are there, and you know, they all have a page number, and it is sited in the index, so it'll be quicker to find).
I hope this helped. :D

I think D as an index tells you what information you need to find and what page, it's also in alphabetical order meaning it's more quicker to locate the information needed