Answer:
d. it specifies the data types that can be used by .NET applications.
Step-by-step explanation:
The .NET Framework Class Library (FCL) makes the system functionality of the .NET Framework available because it contains interfaces, data types, various classes and so on.
It is also important to note that the FCL is integrated to the CLR or Common Language Runtime of .NET Framework which is responsible for code execution.
The Framework Class Library or FCL can be categorized broadly into three:
1. Frameworks
2. Utility features in .NET, and
3. Wrappers around the Operating System (OS) functionality.
1. Frameworks: The FCL contains many frameworks aimed at the development of some applications. For instance, WPF or Windows Presentation Foundation is used to carry out a number of functions but majorly to render user interfaces.
2. Utility features in .NET: This contains a number of classes for use in the .NET framework, examples of these classes include: dictionary, queue, stack, list and so on. Additionally, it contains classes for different manipulations, for example, for handling regular expressions the Regex class is available for use.
3. Wrappers around the Operating System (OS) functionality: Contained in the Framework Class Library are wrappers that are present at the root functionality of the Windows OS. For instance, classes to handle I/O, network features, file system as so on.