That's kind of a personal preference, but in my opinion not really necessary. What if you decide, later on down the road, to shuffle those answers choices? Then you have our choices of with letters display a), b), c),and d) mixed up. Canvas doesn't really know what those letters mean...it only knows the text for each of your answer choices along with whatever choice you mark as "correct". Does that help at all?
Yes it does. Thanks. My reasons for using a), b) etc are two-fold: first, historical continuity with years of written exams using Scantron answer sheets; and second, for ease of editing draft quizzes/exams on Canvas. But neither of those reasons is compelling. Thanks again.
Doing something the way you have always done something is familiar, but not always best or easiest. Trying to mimic on-paper behavior in an online environment is sometimes difficult (for example, the APA style guide was not designed for online discussions).
Here are a couple of reasons to label.
If your question is one of those convoluted "(a) and (b) but not (c)" type questions, then obviously labeling is important. This is a weak argument. You should rewrite those type of questions or use a different question type. Also, shuffling the order of the questions is better for quiz security. It makes it a little (not much) harder for students to share just the answers. For those who are using "all of the above" responses, then New Quizzes has the ability to lock items in place for multiple choice questions and still allow you to shuffle the others.
If you are using images (including equations) in your choices, then the online Quiz Statistics will not show responses containing images. For those of us doing math, our entire answer choices might be an equation object and there was no way to tell the responses apart. One trick involved using a hidden (white on white) letter a, b, c, etc., to identify the choice. It doesn't show up on the quiz statistics, but it does in the student analysis report and we can then tell what the student wrote.
If you feel I'm not making the case for labeling, it's because I'm not. Students get multiple choice questions -- it's the one question they truly get. They don't need the a), b), c) in there. I cannot speak as to how much it helps you with editing, it may actually hurt more than it helps. If you accidentally skip (b) when creating the question, then you have to move everything around, but if they're not labeled and you're going to shuffle answers (which you should), then you just add it to the end. Most of the time, editing time is when you create the question and then you never do it again because you did it right the first time. Edited questions in a quiz don't automatically update in question banks, nor do edited questions automatically update on quizzes (unless they're linked), so it really is best to get it right the first time.
The downsides to labeling are many while the upsides to labeling are few.