Consider the following recursive method, which is intended to return a String with any consecutive duplicate characters removed. For example, removeDupChars("aabcccd") returns "abcd".

public static String removeDupChars(String str)

{

if (str == null || str.length() <= 1)

{

return str;

}

else if (str.substring(0, 1).equals(str.substring(1, 2)))

{

return removeDupChars(str.substring(1));

}

else

{

/* missing code */

}

}

Which of the following can replace /* missing code */ so that removeDupChars works as intended?

A. return removeDupChars(str.substring(2));

B. return removeDupChars(str.substring(1)) + str.substring(0, 1);

C. return removeDupChars(str.substring(2)) + str.substring(1, 2);

D. return str.substring(0, 1) + removeDupChars(str.substring(1));

E. return str.substring(1, 2) + removeDupChars(str.substring(2));