Question mark
In the early 13th century, when the growth of communities of scholars (universities) in Paris and other major cities led to an expansion and streamlining of the book-production trade, punctuation was rationalized by assigning Alcuin's stroke-over-dot specifically to interrogatives; by this time the stroke was more sharply curved and can easily be recognized as the modern question mark.
Rhetorical question
Depending on the context, a rhetorical question may be punctuated by a question mark (?), full stop (.), or exclamation mark (!), but some sources argue that it is required to use a question mark for any question, rhetorical or not.