He kept plugging away in his cubicle, it seemed he was the only person not called into the what?
Options:
- building
- conference
- assessment
- demonstration
- garage
Let's think carefully first. Step-by-step reasoning process:
user
To keep plugging away means to continue working steadily in one place. Conferences and meetings are usually held at work. When one is not called into a conference, they keep working in his cubicle. So the final answer is conference.
assistant