Which statement about abstract classes is true?

Abstract classes are designed to provide a base for other classes while allowing for some method implementations. One key characteristic of abstract classes is that they can implement multiple interfaces. This flexibility enables an abstract class to inherit method signatures from different interfaces, allowing more comprehensive design patterns and facilitating code reuse.

By implementing multiple interfaces, an abstract class defines behaviors that may not be present in the base class, ensuring that any concrete subclass provides the specific implementations for those methods. This capacity to implement interfaces while also being part of an inheritance hierarchy is valuable in object-oriented programming, enabling a more versatile and modular code structure.

The other statements do not accurately define the capabilities of abstract classes, as they can contain both abstract and concrete methods, can only extend a single class (due to single inheritance in many languages), and are meant to facilitate the development of subclasses rather than solely serve as interface definitions.