Ad type criteria cannot be used to create a Custom Segment.
- Ad type
- Sequences of user actions
The correct answer is: Ad type
Explanation: You can not create any segment on the basis of the Ad type, campaign type, or ad group type. A segment is a subset of your Analytics data. Whereas the types of Ads, campaigns, and ad groups don’t find under any metrics or dimensions. You can select the name of the campaign or ad group but can not choose the type of that.
The segment builder lets you create the component filters of a segment based on Analytics dimensions and metrics. You choose a dimension or metric, a comparative operator, and you enter a value to set the condition for the filter.
Read more here: https://support.google.com/analytics/answer/3124493