"Which is my seat?" asked Hana
A. Hana asked which (one) was her seat.
B. Hana asked which seat was hers.
C. Hana asked which her seat was.
Actually I'm completely convinced that sentences A & B are correct, but what about sentence C ? It really surprised me when I found out that Michael Swan, in his "PEU", had accepted it. I can, semantically, absorb such a form with other question words such as "where"____ (Hana asked where her seat was.) But I think the case with "which" is different. The question word "WHICH" needs to be followed by a noun to make sense. That's to say, in direct speech "which (one) is my seat". Here, in direct speech, the noun "ONE" is optional because it's already understood from the context. But In indirect speech, it should be "Hana asked which (one) was her seat" or "Hana asked which one her seat was". But is it OK to say (Hana asked which her seat was)?
Thank you very much