• Rotation priority
• Trafficking rules
• Feed priority
• Prioritized rules

The correct answer is: Prioritized rules

Explanation: Checking that box means that for that particular filterable column, an empty cell means that any value is eligible. This is typically used for the default rule. However, if you have a setup where multiple columns are getting filtered in one rule, it may make sense to check this box, because not every filtering column may contain a value.

Read more here:https://support.google.com/richmedia/answer/4354926