Answer: A
Step-by-step explanation:
We know it's A because of process of elimination.
It can't be B, because she has three weeks, that's plenty of time.
It can't be C, because she hasn't indicated that she needs help at all.
And it can't be D, because local libraries don't tend to have sources from around the world, that's what the internet has. She doesn't really need worldwide sources anyway, since this is an essay about a US president.
The internet is very big, and not every source is trustworthy, so it depends on what websites you go on, but for the most part you can find throrough and reliable research online.