问题：

[单选]

A network includes a RIPv2 domain, an EIGRP domain, and an OSPF domain. Each pair of routing domains has multiple routers redistributing routes between the p air of domains. The design requires that the redistribution configuration avoid matching based on prefix/length because of the trouble in maintaining such configurations.
Which one of the following tools can be used in all three routing domains to attem pt to prevent domain loops?（）

A . Setting route tags
B . Setting the default administrative distance differently for internal and external routes
C . Setting administrative distance differently per route
D . Setting metrics much higher for all ext ernal routes than for all internal route