Microsoft Certified Solutions Developer (MCSD) Certification Practice Test

The keyword that allows you to define a public default constructor in generic type constraints is "new." When using generics in C#, you can specify constraints on the type parameters, which helps to ensure that the types passed as arguments to a generic class or method meet certain criteria. The "new" keyword allows you to specify that a type parameter must have a public parameterless constructor. This is useful when you want to create instances of the generic type within the class or method, ensuring that any type used as a type argument can be instantiated without needing any parameters.

For example, when you declare a generic class and include the "new()" constraint for a type parameter, it guarantees that any class that is used as a type argument will have a default constructor available. This is crucial for scenarios where you might want to create objects of that type dynamically in your code.

The other keywords provided do not serve this purpose: "init" is related to properties for initialization in C# 9.0 and later, "default" is used in generic contexts but does not define constructors, and "override" is utilized for overriding methods in inheritance hierarchies, not specifically for constructors. Therefore, "new" is the most appropriate choice for defining a public default