Problem of the Day
Problem:
A company rents vehicles for transporting people's belongings from one place to another, and uses software to track their inventory. The software uses classes for Rental, PoweredVehicle, Truck, Van, and Trailer (for clients who want a trailer for their own vehicle or for a truck). How should the classes be structured to make good use of inheritance?
The correct answer is c. The upward arrow that points from a sub-class to a super-class indicates an "is-a" relationship: a Trailer "is a" Rental, and a Van "is a" PoweredVehicle which in turn "is a" Rental itself.