This doesn’t help. Even if other predators did not move into the area after the wolves were introduced, the wolves themselves are predators, and we would expect the moose herd’s growth to have been impacted by their presence.

This doesn’t help. We’re looking for the reason why this particular attempt to control the moose population did not work, not other examples of failed attempts.

This is what we need. If wolves often kill sick moose, they’re protecting the healthy moose from contracting illnesses which might have otherwise killed off more moose and slowed the population’s growth. Also, the diseased moose the wolves kill presumably would have died anyway.

This is irrelevant. We’re not looking for information about how much vegetation healthy vs. diseased or injured moose eat, and this answer choice tells us nothing about what happened when the wolves were introduced.

We’re not interested in moose that are too old to breed, because the factor we’re examining is population growth. Furthermore, even if older moose are just as likely to die of natural causes, wolf attacks would still presumably kill additional moose, both older and younger.