In Yellowstone National Park, Old Faithful is a geyser that is named because of its consistency. It faithfully erupts on average every 90 minutes. What type of function would best model the water output per minute from Old Faithful?

A. an exponential function
B. a quadratic function
C. a periodic function
D. a linear function

C. a periodic function

is this right?

Yes, you are correct. The water output from Old Faithful follows a consistent pattern of erupting every 90 minutes, indicating a periodic function.