Which of the following choices is phrased as an arguable topic? Should police have the right to stop protests?
Did Bull Connor use police dogs on protesters?
Curfews are often used to discourage public protests.
Children marched in Birmingham, Alabama.

the first one. the rest are just statements

1. Should police have the right to stop protests?

Explanation:

That is an arguable topic because you can argue violent protesting, the constitution, etc.

Why not?:

2. You can't use that as an arguable topic because it is a fact that Bull Connor used police dogs on protesters.

3. You can't use that because it is already a fact that curfews are sometimes enforced to discourage protests, we've seen that happen over this last year.

4. You can't use that because, like choice 2, it is a fact.

Hope this helps, let me know if you have any questions :)