And the answer is... Unicron!
6 seconds sound clip from the The Transformers: The Movie movie soundboard.
You can hear this line at 01:06:16 in the Blu-ray version of the movie.
Quote context
[...]
- Look, he's alive! He's alive, I don't believe it!
- No! (2)
- Where's Galvatron? Where is he?
- And the answer is... Unicron!
- Then we've got to destroy Unicron.
- Yes, friends, and now destroy Unicron.
- Eliminate even the toughest stain.
[...]