A is correct because RSTP alternate ports block traffic while receiving superior BPDUs from a neighboring switch. An alternate port is a backup port for a root port, which means it receives better BPDUs from another bridge than the current root port. However, an alternate port does not forward any traffic, as it is in a discarding state. It only listens to BPDUs and waits for the root port to fail. If the root port fails, the alternate port can immediately transition to a forwarding state and become the new root port.
C is correct because RSTP alternate ports provide an alternate higher cost path to the root bridge. An alternate port is selected based on the same criteria as the root port, which are the lowest bridge ID, the lowest path cost, the lowest sender port ID, and the lowest receiver port ID.
However, an alternate port receives a higher cost BPDU than the root port, otherwise it would be the root port itself. Therefore, an alternate port provides an alternate higher cost path to the root bridge than the root port.

Option A is correct. Creating multiple areas in OSPF can help to reduce the convergence time .
This is because changes in one area do not affect other areas, so fewer routers need to run the SPF algorithm in response to a change.
Option D is correct. Creating multiple areas in OSPF can help to reduce Link State Advertisement (LSA) flooding across the network. This is because LSAs are not flooded out of their area of origin.

The router with the highest OSPF priority becomes the DR. In this case, R2 has a higher priority (64) compared to R1's priority (32). Hence, R2 will become the DR.
The router with the next highest priority becomes the BDR. Since R1 has the next highest priority after R2, R1 will become the BDR.

The default hold-time is 90 seconds, meaning that the default frequency for keepalive messages is 30 seconds.
https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/ref/statement/precision-timers-edit-protocols-bgp.html#:~:text=BGP%20on%20the%20local%20routing,keepalive%20messages%20is%2030
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Nonstop active routing's defining architectural feature is that the backup Routing Engine runs a fully live, active instance of the routing protocol daemon (rpd) in parallel with the primary Routing Engine's rpd instance, continuously, from the moment NSR and its prerequisite GRES are established - not merely at the instant a switchover begins. As protocol adjacencies form, routes are learned, and the RIB is updated on the primary Routing Engine, that same protocol and RIB state is mirrored in real time to the backup Routing Engine's rpd process through an internal synchronization mechanism, so the backup's protocol state remains a live, up-to-date replica of the primary's at essentially every moment during normal operation. When a switchover occurs, the backup Routing Engine simply assumes the primary role with protocol adjacencies, routing tables, and forwarding state already fully populated and current, allowing it to continue operating without re-establishing neighbor relationships or re-learning the network topology, which is what makes the switchover genuinely nonstop and invisible to neighboring routers. This is fundamentally different from graceful restart, where the restarting router must rebuild its state by requesting help from cooperating neighbors after the fact. The Packet Forwarding Engine plays no role in synchronizing protocol-layer information such as LSAs or BGP updates; that is strictly an rpd-to-rpd function coordinated through the Routing Engine synchronization infrastructure. Reference topics: Junos Enterprise Routing - High Availability, Nonstop Active Routing Architecture and rpd Synchronization.