Why does it make sense to give definition for a pure virtual function?

Question

Scott said on Effective C++, 3rd Edition, pg. 43 that to make an abstract class, we just need to give it a pure virtual destructor:

class AWOV {                      


        

Answer 1

Making it pure forces derived (non-abstract) classes to implement their own.

Providing an implementation allows derived classes to invoke base class behavior (which destructors do by default).