Select all true statements about the input variable of this function.
Distance is the input.
Time of day is the input.
Time since the person starts walking is the input.
t represents the input.
d represents the input.
The input is not measured in any particular unit.
The input is measured in hours.
For each input, there are sometimes two outputs.
It costs $3 per hour to park in a parking lot, with a maximum cost of $12. Explain why the amount of time a car is parked is not a function of the parking cost.