Final answer:
The correct form to complete the sentence is 'está' because it refers to a temporary state or condition in this case.
Step-by-step explanation:
The correct form to complete the sentence is está.
In this case, estar should be used because it refers to a temporary state or condition. The meeting is taking place in the conference room, which is a specific location at that moment.
If we were talking about the permanent location of the meeting, we would use ser. For example, La reunión es en el edificio principal (The meeting is in the main building).
Learn more about Spanish verb conjugation