OPTIONS SETS - Filtrar por uno y solo uno. Filter by one and only one

Hello.
I put in context…
I have “Events” which in a data type It has a “List of Activities” to go placing the progress that are having the events. The “Activities” have a field “Label” which are an “Option Set”.
To which my question is the following one…

I want to place in a table the “Events” that have as “Label” one and only one type of “Option Set” so if they also have other “Option Sets” in the “Label”, do not bring them to the table.

I show you what i try…