下面程序段的输出结果为( )。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 Obj 1 = new Test(12,45 ); System.out.println("a="+Obj1.a+" b="+Obj1. b); Test Obj2 = new Test(); System.out.println("a="+Obj2.a+" b="+Obj2. b); }}

A．a=100 b=200 a=12 b=45

B．a=12 b=45 a=100 b=200

C．a=12 b=200 a=100 b=45

D．a=100 b=45 a=12 b=200