You write the Gb in the base; no chord members must be doubled because it's a seventh chord. To spell the rest of the chord you would find common tones between the last chord and the current tones (If the soprano had G in the previous chord give the soprano G in this chord). Once you've found your common tones, you'd then find close tones (if the tenor had Eb in the last chord give him D in this one). You then give the remaining chord member to the last part.
It's most likely gonna be D
Answer:
Well I don't know what I would do, but this is something you have to answer on your own. It's that type of question where it's asking you what you would do, just think.
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