Unfortunately there are some species of birds that because of man's carelessness are severely in danger and ..... extinct in near future.
1. would become2. become3. have become4. will become
( What's wrong with No.4 ? )
The answer key says No.1 is the correct one here. They drive me crazy !!
Yes, indeed, it's #4.
Your answer key seems to be wrong!
I think that answer is wrong - though it might be the best of the bunch. The following are all more truthful:
5. may become
6. might become
7. could become
8. will possibly become
9. will probably become
PS: On second thoughts, the above refers to species that have been named and identified. If we haven't identified which birds, then yes, there are species which will become extinct, but we don't know which ones yet.