Dominant 7th chord fingerings for piano

What are the fingerings for dominant 7th of C major? Is it 1234, 1234, 1234' 1234' 1234? Or is it 4 instead of 3? My piano teacher said something about 3 but I'm not so sure whether it's a 3 or a 4.

Please take your time to answer and reply. I have an exam in less than a week so please take your consideration to answer my question.

Your fingering makes no sense to me. However, fingering in an exam situation is not something the examiner will be looking at. Fingering in the f="https://forum.tuteehub.com/tag/syllabus">syllabus f="https://forum.tuteehub.com/tag/books">books is only a suggestion, although it usually turns out to be the best option for most folks. S/he only wants to hear correct, regularly played notes, so how you finger them is how you are most comfortable. Dominant 7th of C maj. could be C E G Bb, with the one black key, or could be construed as G B D F, with none. If the former, then Bb can be played with a thumb. It's usually best not to use thumb on black keys, when there's an alternative, as it's the shortest digit, and puts the hand further from the player, but as any alternative is not as f="https://forum.tuteehub.com/tag/good">good, use the thumb. Seems quite late to be considering this, with an exam a f="https://forum.tuteehub.com/tag/week">week away!