Q.) In which of the following cases the minimum no of insertions to form palindrome is maximum?

 in string of length one, string with all same characters and a palindromic string the no of insertions is zero since the strings are already palindromes. to convert a non-palindromic string to a palindromic string, the minimum length of string to be added is 1 which is greater than all the other above cases. hence the minimum no of insertions to form palindrome is maximum in non-palindromic strings.