196.

Which design pattern is shown below? 

public class A
{
  private static A instance;

  private A() {}

  public static A Instance
  {
    get 
    {
      if (instance == null)
      {
        instance = new A();
      }
      return instance;
    }
  }
}

In software engineering, the singleton pattern is a design pattern used to implement the mathematical concept of a singleton, by restricting the instantiation of a class to one object. This is useful when exactly one object is needed to coordinate actions across the system