Prefix mismatch would more likely cause routing issues, but it is not directly related to the LSP breaking, as LSPs are built using label information rather than IP prefix information directly.
A & C are correct
The label bindings must correspond to the prefixes and subnet masks in the routing tables.
If there's a mismatch, the labels will not be used properly, causing the LSP to fail.
i think E is incorrect, if MPLS is not enabled on the routers, there won’t be any LSPs to break.
https://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/mpls/23565-troubleshoot-mpls-vpn.html#cause:~:text=If%20label%20bindings,devices%20will%20fail.
Correct and taken from the link you provided:
If label bindings are received from a downstream neighbor for prefixes (including subnet mask) which do not appear in a router's routing and CEF tables, these bindings will not be used. In a similar manner, if a router advertises labels for a subnet/subnet mask pair, which do not correspond to the routing updates also advertised by this router for the same subnet/subnet mask pair, these labels will not be used by upstream neighbors and the Label Switched Path (LSP) between these devices will fail.
AC
A: Like many other protocols, LDP first establishes a (neighbor adjacency) before it exchanges label information. and each router has unique LSR.
C: When we use LDP on Cisco IOS, we locally generate a label for each prefix that we can find in the RIB, except for BGP prefixes. This information is then added to the LIB (Label Information Base).
The information in the LIB is used to build the LFIB (Label Forwarding Information Base). When the router has to forward a packet with a MPLS label on it, it will use the LFIB for forwarding decisions.
I don't think E is accurate as if MPLS not enabled the Adjacency between the PEs will not form the start, my hint the question asking about already formed session and got broken.
https://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/mpls/23565-troubleshoot-mpls-vpn.html#cause
I think its CE
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