单项选择题

有如下程序
public class Test
int a,b;
Test ( )
a = 100;
b = 200;
Test(int x, int y)
a = x;
b = y;
public static void main(String args[])
Test Obj1 = new Test(12,45);
System.out.println("a = "Obj1.a+" b = "+Ob31.B) ;
Test Obj1 = new Test();
System.out.println("a = "Obj1.a+" b = "+Obj1.B) ;
程序的运行结果为( )。