A. I’d advise just to turn in the first five pages, even if it ends in the middle of a sentence. In fact, that can be helpful to you. If you hook an agent with your first five pages, and then it abruptly ends in mid-thought, they are immediately going to request more because they want to know what happens next.
That said, if you want to try and squeeze in a sentence or two at the end of page five, you can. But, in theory, it shouldn’t be necessary.
If you’re having trouble with the start of your story, check out Noah Lukeman’s The First Five Pages.