What does AppleTalk update routing provide an improvement on?

The correct choice highlights that AppleTalk update routing specifically improves the Routing Table Maintenance Protocol (RTMP). RTMP is crucial for routing information within an AppleTalk network by allowing routers to communicate changes in the network's topology efficiently. By updating routing information dynamically, RTMP ensures that routers can adapt to changes such as new devices being added or removed from the network. This capability leads to enhanced network efficiency and reliability, minimizing the time it takes to converge after a network change.

In contrast, other options do not directly relate to the specific improvements brought by AppleTalk update routing. The session protocol is more concerned with managing sessions between applications rather than routing decisions. Asynchronous Transfer Mode (ATM) refers to a different technology altogether focused on switching methods rather than routing protocols. Access Units pertain to data transmission aspects, but do not play a role in routing updates within AppleTalk networks. Therefore, the focus on RTMP's enhancement through AppleTalk update routing is key to understanding its significance in network design.