\begin{tabular}{l} An abstract class will: \\ Have fewer zero function pointers in its vtable \\ than concrete classes have \\ \hline Have all zero function pointers in its vtable. \\ Have at least one zero function pointer in its \\ vtable. \\ Share a vtable with a derived class. \\ \hline\end{tabular}

An abstract class is a way to define a blueprint for other classes in object-oriented programming. It can’t be instantiated directly and usually includes one or more pure virtual functions, meaning it requires derived classes to implement these functions. This results in an abstract class having at least one zero function pointer in its virtual table (vtable), which helps the compiler know that certain functionality must be provided by subclasses. When dealing with abstract classes, a common mistake is trying to instantiate them directly. Be aware that doing so will typically lead to compilation errors, as they are designed only to be a foundation for more specific concrete classes. Instead, focus on implementing the necessary methods in derived classes to make use of the abstract class’s potential!