问题：

[单选]

Refer to the exhibit. In this network， R1 has been configured to advertise a summary route， 192.168.0.0/22， to R2. R2 has been configured to advertise a summary route， 192.168.0.0/21， to R1. Both routers have been configured to remove the discard route （the route to null created when a summary route is configured） by setting the administrative distance of the discard route to 255.What will happen if R1 receives a packet destined to 192.168.3.1？（）

A . The packet will loop between R1 and R2.
B . It is not possible to set the administrative distance on a summary to 255.
C . The packet will be forwarded to R2， where it will be routed to null0.
D . The packet will be dropped by R1， since there is no route to 192.168.3.1.