Which two conditions can cause an LSP to break between two PE routers? (Choose two.)

A lost LDP adjacency will cause an LSP to break because LDP (Label Distribution Protocol) is responsible for exchanging labels between routers. Without this adjacency, routers cannot learn or distribute labels, making LSP establishment impossible. A prefix mismatch means the destination prefix advertised by one PE router is not recognized or is different from what the other PE router expects. This prevents the establishment of a complete end-to-end LSP, as the path cannot be resolved. Matching labels are necessary for an LSP to function, not a cause for it to break. IGP hello adjacency is crucial for routing, but its direct loss doesn't immediately break an established LSP; it would eventually lead to routing table instability, which could then impact LDP. MPLS not being enabled would prevent LSPs from forming in the first place, rather than causing an existing one to break.