Which phrase describes a claim that is "debatable"?

1. An idea to be shared in front of a group of people
2. An idea that can be supported by facts
3. An idea about a topic that is not grounded in evidence
4. An idea that is open to discussion

4. An idea that is open to discussion

Option 4 - "An idea that is open to discussion" - describes a claim that is "debatable."

To arrive at this answer, let's break down the different options:
1. "An idea to be shared in front of a group of people" refers more to the act of sharing an idea rather than its potential for debate.
2. "An idea that can be supported by facts" refers to the requirement for an idea to have factual evidence, but it does not explicitly mention debate.
3. "An idea about a topic that is not grounded in evidence" suggests the absence of evidence, but it does not directly address the concept of debate.

On the other hand, option 4 - "An idea that is open to discussion" - explicitly states that the idea is subject to debate. This implies that there can be differing viewpoints and opinions, making it a debatable claim.

The phrase that describes a claim that is "debatable" is option 4: An idea that is open to discussion.