Final answer:
The function f(p) = 20 is constant, meaning it always returns 20 irrespective of the number of packages. Thus, the range for the given situation is just the single value 20.
Step-by-step explanation:
Since the function is constant, regardless of the number of packages (p), the function will always return the value 20. Hence, the maximum range of the function in this context is just a single value, which is 20. This is because the number of trips remains identical irrespective of the package count, as long as it does not exceed the specified daily transport capacity of 6,000 packages. Consequently, option (d) 20 to 6,000 is incorrect because the function does not depend on the number of packages to return a value greater than 20. The correct answer is that the range is the single value 20.