The United States Navy announced that, beginning next year, they plan to close several of their bases in order to reduce

Option A - incorrect
The wrong use of pronouns. This option uses the plural pronouns 'their' and 'they' to replace the singular subject 'the United States Navy.' Whereas the subject is a singular subject and it requires a singular pronoun 'it.'

Option B - incorrect
This is incorrect as it uses the wrong pronoun to modify the subject just like it does in option A.

Option C - correct
This answer choice uses the correct form of pronoun to modify the subject. I.e it modifies the subject with the singular pronoun 'it.'

Option D - incorrect
It has the same issue as option A and B above. It uses the pronoun 'their' and 'they' to modify the singular subject 'the United States Nacy.'

Option E - incorrect
This option seems partially correct but it is wrong because it firsts modifies the subject with the singular subject 'it.' Then, it modifies the same subject with a plural pronoun 'their'. So, therefore, it is wrong.