Network survivability mechanisms are broadly categorized into protection and restoration. Protection is a proactive strategy where backup resources, such as a secondary path and its required bandwidth, are pre-allocated and reserved at the time the primary service is established. This allows for very fast, often sub-50ms, recovery. In contrast, restoration is a reactive strategy. It initiates the process of finding and allocating backup resources only after a failure has been detected. While restoration is generally slower than protection, it is more resource-efficient because backup capacity is not dedicated and can be used for other purposes until a failure occurs.

A: Incorrectly defines restoration. Restoration is a dynamic recovery process, not a specific pre-configured scheme like 1+1 protection.

B: Incorrectly defines protection as allocating resources upon failure; this is the definition of restoration.

C: Incorrectly swaps the definitions of protection and restoration.

1. Official Vendor Documentation: Nokia 7750 SR and 7950 XRS GMPLS-UNI, RSVP-TE, and OSPF-TE for LSPs Guide, SR OS Release 22.10.R1. In the "LSP Redundancy" section, the guide distinguishes between pre-provisioned backup LSPs for fast reroute (a protection mechanism) and the signaling of secondary paths upon primary path failure (a restoration mechanism). This aligns with the definitions of pre-allocation for protection and allocation-upon-failure for restoration.

2. Peer-reviewed Academic Publication: Ramaswami, R., Sivarajan, K. N., & Sasaki, G. H. (2010). Optical Networks: A Practical Perspective (3rd ed.). Morgan Kaufmann. In Chapter 13, "Protection and Restoration," Section 13.2, the authors state: "In protection schemes, the backup path and resources are reserved for a connection at the time the connection is set up... In restoration schemes, the backup path and resources are discovered dynamically after a failure has occurred." This directly supports the definitions provided in the correct answer.