阅读下面的程序,选择正确的答案?() class StringDemo{ public static void main(String[] args){ String s1 = “a”; String s2 = “b”; show(s1,s2); System.out.println(s1+s2); } public static void show(String s1,String s2){ s1 = s1 +”q”; s2 = s2 + s1; } } A. ab B. aqb C. aqbaq D. aqaqb