As the wolves with short hair decreases (because the environment does not encourage their survival), there will be less competition for the food that both would need. The long haired wolf even with a recessive gene, would increase in number.
A might be true but the hair length by itself will not cause the extinction of the entire wolf population.
C is simply not true. Your givens tell you that the long hair are more likely to survive.
B is the answer, for the reason given above.
