When I asked an earlier question I wasn't sure whether to put a question mark at the end of the following sentence, which is, obviously, a question, even if it is not written in interrogative form:
Since I suppose both are grammatical, I wonder which one, "A" or "B", sounds more natural English?
The question is: is ending that sentence with a question mark obligatory?
Best Answer
As a matter of language, no punctuation is ever obligatory. In speech, there are no periods, commas, dashes, question marks, ellipses, diareses, graves, aigus or any other points. Punctuation is merely mark-up intended to make the linguistic substance more understandable in the absence of important linguistic information such as pauses and intonation.
So you punctuate to make your structure and intention clear. "I wonder which sounds more natural" has the form of a statement, and could be interpreted as merely a report on your present uncertain state of mind. That interpretation would be modestly reinforced by pointing with a period. More likely, however, particularly given the context, you are describing your uncertainty in the hope that someone will resolve it. That is almost certainly how it will be interpreted; and you may explicitly dismiss any ambiguity by pointing with a question mark.
A question mark is not obligatory, but it is recommended, as a cue to your reader.