A. Your grandparents’ house/ theirs
Answer:
The first one is 2 and the second one is none of the above
It would be a subordinate cause, for it can't stand on its own. Think about it: Since early this morning. What happened since early morning? Since it doesn't provide that information, it wouldn't be able to be an independent cause.
Also, I don't believe that the sentence is grammatically correct :)
Turkey's is the possessive noun
