Q1:

Which of the following are necessary for Run-time Polymorphism?

1. The overridden base method must be virtual, abstract or override.
2. Both the override method and the virtual method must have the same access level modifier.
3. An override declaration can change the accessibility of the virtual method.
4. An abstract inherited property cannot be overridden in a derived class.
5. An abstract method is implicitly a virtual method.