While editing a story I came across a sentence like this:
I shook my head and said 'No'.
I can think of at least five possible ways to punctuate that:
A. I shook my head and said, "No."
B. I shook my head and said, 'No'.
C. I shook my head and said 'No'.
D. I shook my head and said no.
E. I shook my head and said no.
It's surely not wrong to use A, treating a single word as ordinary dialogue, but it uses a lot of punctuation marks for one short word.
I cannot find it now, but I'm almost certain I've seen a recommendation in CMOS that E is okay.
I'm not sure which Americans would prefer, but I think most of those writing in BrE would prefer C instead of B.
Before I'd considered the possibility of italics, the one I preferred was the author's first choice, C. I wrote a comment advising them that they were free to choose whatever style they wanted, so long as it was obviously what was meant the first time it was used and they were consistent in always using that style.
Then I came across another sentence which was like this:
She handed me the phone and I said "Hello?"
It's not explicit, but I commented that the context was sufficient for readers will have no doubt that the MC spoke into the phone.
I objected to the author's inconsistency, saying they must either use single quote marks again or a comma after 'said' to treat the word as dialogue.
The question mark as part of the speech changes things. E no longer seems acceptable as it results in either a question mark followed by a full stop, or ambiguity over whether the question belongs with the spoken word or is showing the entire sentence is a question.
My current thinking is I'd prefer both No and Hello? in italics with an initial uppercase, i.e.
I shook my head and said No.
She handed me the phone and I said Hello?
I cannot see readers misinterpreting those and it doesn't need any additional punctuation marks.
What do others think?