Final answer:
Captive propagation is not a determining cause of species endangerment or extinction.
Step-by-step explanation:
The factor that is NOT a determining cause of species endangerment or extinction is B. Captive propagation. Captive propagation refers to the breeding and raising of endangered species in captivity in order to reintroduce them into the wild. While captive propagation can be a conservation strategy to help recover populations, it is not a causal factor in species endangerment or extinction.