To answer this question we need to understand the difference between discrete and continous data:
• Discrete data can only take certain values along some interval.
,
• Continuous data can take any value along some interval.
In this case we know that there will always be a integer number of people in the meeting, that is, we can only have certain values (we can't have 6.5 people in a meeting).
Therefore, this is a discrete data set.