Answer: C. Preying
Step-by-step explanation:
A non-native species is the species which is introduced to a new ecosystem. This species is introduced intentionally or accidentally to a new ecosystem by human beings or they may enter to the ecosystem by their own.
A non-native species can be invasive which means it can compete with the native species for resources like shelter, food and mates.
According to the given situation, the Gila trouts being the native species has been affected by the non-native Rainbow trout. This may be because of the fact that non-native species can be invasive for the native species. As the species is used as mate by the non-native species and they may become the prey of non-native species. This has resulted in the extinction of the species of Gila trouts.