单项选择题

当执行下面代码时，会输出( )。 Boolean b1 = new Boolean(true); Boolean b2 = new Boolean(true); if (b1 == b2) if (bi.equals(b2)) System. out.printin ("a"); else System. out. println ("b"); else if (bi.equals(b2)) System. out.println ("c"); else System. out.printIn("d");