The scenario that can be modeled by a linear function is:
the total pay of a person whose rate of pay per hour is fixed at $15 per hour.
This scenario can be represented by the linear function \( y = 15x \), where \( y \) is the total pay and \( x \) is the number of hours worked. Each additional hour worked results in an additional $15 in total pay, creating a straight-line relationship.
The other scenarios involve varying rates of pay, which would typically result in non-linear relationships.