Refer to the exhibit. An engineer at ISP C is configuring a new interconnection with ISPs A and B using the BGP protocol. After the initial configuration, the engineer noticed high memory usage and…

This command applies a filter, identified by access-list number 1, to limit the labels accepted from LDP neighbor 11.11.11.11. By only accepting labels for a defined set of prefixes, the router's Label Information Base (LIB) size is reduced, consequently lowering memory consumption.

A standard ACL (like ACL 1) is used to define the specific prefixes for which R2 should accept MPLS labels from its LDP neighbors. By explicitly permitting only the necessary prefixes in this ACL, R2 avoids learning and storing labels for all received prefixes, thereby minimizing LIB growth and memory usage.

While an extended ACL can define prefixes, a standard ACL (like ACL 1, as used in option A) is typically sufficient and simpler for filtering prefixes for LDP label acceptance.

This action applies an extended ACL (ACL 101) to neighbor 1.1.1.1. This could be part of a solution, but without `Configure Extended ACL 101` explicitly mentioned as a required part, it's an incomplete option in context of A and B forming a complete pair.

This action applies an extended ACL (ACL 101) to neighbor 21.21.21.21. Similar to option D, it is an incomplete solution without configuring ACL 101 itself, and (A) and (B) provide a complete and coherent solution using a standard ACL.