How should long comments be formatted inside a Python list?

If most comments are short, option B is reasonable and keeps the list compact. Once several comments need multiple lines, switch to C so the list remains consistent. Option A interrupts the visual flow because the comment is separated from the item it describes.

For two or three lines, aligned continuation comments like B are fine. For very long descriptions—perhaps twenty lines or more—use C. The important thing is to avoid making the formatting depend on the length of a neighboring comment, since that creates unnecessary maintenance work.

Option C is usually the most maintainable. Put each description above its item, regardless of whether it takes one line or several. That keeps the formatting consistent and avoids having to realign a whole column when one comment changes. For regular expressions or other complicated values, consider storing each item with its description in a tuple, dictionary, or small data class so the explanation stays attached to the data and can also be displayed when debugging.

Try to keep ordinary entries on one line and accept an occasional line that exceeds your preferred width if that is the clearest result. If a comment regularly needs several lines, that may indicate the explanation belongs in the data structure or in a separate description rather than as an inline comment.