问题：
[单选] During a recent OSPF election among three routers, RTA was elected the DR and RTB was elected the BDR, as seen in the graphic. Assume that RTA fails, and that RTB takes the place of the DR whi le RTC becomes the new BDR. What will happen when RTA comes back online？（）
A new election will take place establishing an all new DR and BDR based on configured priority levels and MAC addresses.。 RTA will take the place of DR immediately upon esta blishing its adjacencies.。 RTA will take the place of DR only if RTB fails.。 RTA will take the place of DR only if both RTB and RTC fail.。
