A lot of that sort of information might be exam-specific, which is where there would be more fixed expectations. In general usage, I don't think you have to include parts of the question in order to answer it:
Qu- What time is it?
This strikes me as a perfectly valid answer to a question. In some cases, it might be more appropriate to give a fuller answer, but it is just adding words to expand the answer, which could be to aid the listener or to make the answer more grammatically complete, but in most circumstances the answer above would be fine.
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