The second choice is a fragment, not a complete sentence.
I believe the correct choice is number one, because if you turn the sentence around, it answers the question of why the crowd is gathered. You may want to confirm on the website chompchomp.com (Grammar Bites).
Answer:
D) The Speaker constantly made announcements, but they weren't all important.
Explanation:
It's been a while since I've read The Giver but this option makes the most sense to me.
I guess it would either be mood or syntax
