Explain different types of inheritance.

Inheritance in OOP is of four types:

1. Single inheritance - Contains one base class and one derived class
2. Hierarchical inheritance - Contains one base class and multiple derived classes of the same base class
3. Multilevel inheritance - Contains a class derived from a derived class 
4. Multiple inheritance - Contains several base classes and a derived class 

All .NET languages supports single, hierarchical, and multilevel inheritance. They do not support multiple inheritance because in these languages, a derived class cannot have more than one base class. However, you can implement multiple inheritance in.NET through interfaces.