Which sentence contains two independent clauses and a dependent clause?

a- after battling it for several days, john remained at home because he had a sore throat.

b- here is the money i owe you, and now i am happy to be free of debt.

c- fred had become very serious about his goals, and he was no longer consistently a practical joker.

d- since we had gone only a mile from camp, we could return before dark and we would not become lost.