I am pretty sure the correct phrasing would be b or d... the the one i would chose would be d.
hope this helped! :)
You didn't include the complex sentences so I don't know how to help you but a subordinate clause is a clause that can't become a stand alone sentence and can only be used with an independent clause.
The two sales reps, Peter and I, handled the business when the owner went on vacation.
I think the answer is d but not really sure but hope i have been a help
