It really is hard to say because there are many slots and we do not know what your teacher is teaching. I have seen a lot of teachers teaching out of date material. With that said, here is a list from best to worst.
PCI Express x16
PCI Express x1
AGP
PCI
This is list is based on greatest to least and base on the bandwidth read and write speed.
I don’t get this but you just put random number
The subject is generally covered inside the body of text, so that one's out.
The footer is a completely separate part of the document, specifically the bottom-most portion of the page, but let's look at the others.
The salutation is placed at the beginning of the body of text.
And your closing note is placed at the end of the body of text.
So, the best answer would be b. footer.
