Canadianer has very deftly enabled me to arrive at the answer with knowledge I already had. I attempt to explain the same here.
We know that eukaryotes and prokaryotes have different RNA polymerase (enzyme responsible for transcription) enzymes. Eukaryotes have three different RNA polymerase, each responsible for synthesis of the three different types of RNAs. RNA Polymerase II is responsible for mRNA synthesis in eukaryotes. It recognises the eukaryotic (or say, human) promoter present in an eukaryotic cell. On the other hand, in prokaryotes, there's only one RNA polymerase responsible for synthesis of all the types of RNA.
Coming to the question, using a human promoter is probably logical since it would be ideal for initiation of transcription of the said human gene Y. But this is not true because a promoter is only responsible for recognition by RNA polymerase and allowing it to move further and transcribe the DNA sequence i.e. it doesn't matter what comes after a promoter. Also, prokaryotic RNA polymerase is unlikely to recognise the sequence of a human promoter. It is much more likely to recognise a bacterial promoter. Since a promoter's function is limited to allow recognition, it doesn't matter that it's a bacterial promoter as long as it can be recognised.
The two options about operators weren't a confusion for me since I already know that they don't have much to do with expression of gene as much as regulating it. Besides, any operator used would also require a promoter in any case, since that is how transcription is initiated.
Thus, the scientist should use a bacterial promoter.