Option D: 'Announce' is a verb that forms a noun with 'ment': announcement.
'Announcement' means 'a formal public statement about a fact or event'.
The suitable form is a noun because it 'announcement' is the object of the verb 'made'.
The object is always a noun. Hence, option D is correct.
Option A: 'Announce' forms a noun with 'er': announcer.
An 'announcer' is a person who announces something. 'Announcer' refers to the person who announces, whereas the sentence mentions what he announces.
The sentence does not mention any person making an announcement, and hence this noun isn't suitable.
Option B: 'Announce' forms a gerund/present participle with 'ing': announcing
'Announcing' is a gerund or a verb form + ing. But, it does not form a complete meaningful sentence, as the verb 'made' requires a noun and not a gerund.
Option C: The word 'announceship' does not exist in standard English language.
Hence, options A, B and C are wrong.