正解:A
Bootstrap Router is the standards-based mechanism that supports dynamic RP discovery in a PIM sparse- mode domain. Cisco documentation distinguishes Auto-RP, which is Cisco-proprietary, from BSR, which is defined for standards-based RP distribution. With BSR, candidate RPs advertise their availability, and the elected bootstrap router distributes RP-set information throughout the PIM domain. This removes the operational burden of manually configuring the same static RP information on every multicast router. Anycast- RP provides RP redundancy and load sharing but does not by itself provide standards-based dynamic RP discovery across the domain. Static RP is simple but not dynamic. Auto-RP can dynamically distribute RP information, but it is not the standards-based answer. The design value of BSR is most visible in large multicast domains, where routers need consistent RP information and manual changes are risky. Therefore, when the question asks for a standards-based RP deployment that supports dynamic RP discovery, the correct answer is bootstrap router. Reference topics: PIM sparse mode, Bootstrap Router, candidate RP, RP-set distribution, dynamic RP discovery.