Answer:
It will be discrete.
Explanation:
The yearbook club has 5 members returning from last year.
An average of 3 new members sign up each day.
This means each following day the members increase with 3.
We can represent this information in an equation as:

And the series will form like : 5,8,11,14,17........
Hence, we can say that the graph will be a discrete function as the members will be whole numbers and not partial and the booth is also set up once every day,