Over population if i recall correctly
Is there more to this problem?
Answer: C. Black snakes will not prey on cane toads in areas where cane toads have been present for 40–60 years.
Explanation:
Cane toad secret a toxin called bufotoxin which is a defense mechanism against predators. These defense mechanism is capable of killing black snakes if they eat cane toads. Within a period of 40 to 60 years, the black snakes in these area will be aware of the presence of a toxin capable of killing them in cane toads and will not prey on them. This phenomenon is termed learned behavioral adaptation.
The hybrid zone may change depending on the fitness strength and the reproductive barriers of the hybrids.