GWD31 4-q27 请求解释~~~

Q27:

In parts of the Caribbean,
the manatee, an endangered marine mammal, has long been hunted for its
meat.  Having noted the manatee hunters’
expert knowledge of manatees’ habits, local conservationists are encouraging
the hunters to stop hunting and instead to take tourists on boat rides to see
manatees.  Tourist interest is high, so
the plan has promise of achieving the twin goals of giving the former hunters a
good income and helping ensure the manatees’ survival.

Which of the following, if true, raises the most serious
doubt about the plan’s chance of success?

1. Many
        tourists who visit these parts of the Caribbean
        are uninterested in manatees and would not be willing to pay what the
        former manatee hunters would have to charge for boat rides to see
        manatees.
2. Recovery
        of the species would enable some hunting to continue without putting the
        manatees’ survival in jeopardy again.
3. In
        areas where manatees have traditionally been hunted for food, local people
        could easily replace the manatee meat in their diets with other foods
        obtained from the sea.
4. There
        would not be enough former manatee hunters to act as guides for all the
        tourists who want to see manatees.
5. To
        maintain their current income, manatee hunters who switched to guiding
        tourists would have to use far larger boats and make many more trips into
        the manatees’ fragile habitat than they currently do.