boolean isPal (String s)Show the Activation Stack for "ZEROREZ"{== 0 || S. length ()if (a.length ()// if length =0 OR 1 then it is== 1)return true;if (scharAt (0) == .charAt (s.length ()-1))// check first and last char of String:// if same then do same for substring// for substring and carry on this// remove first and last char.return isPal (s.substring (1, 8length () -1)):ww ww// if its not the case than string is not.return false;}

The given problem is related to the Stack data structure that is being used in the given function. The function takes on string s and checks whether the passed string is palindrome or not which returns true when reading a string from backward results same as reading the string from starting character.The requirement is to check the stack data states with the string ZEROREZ Start the stack that has these characters as below: Index Stack Contents 6 Z-Top 5 E 4 R 3 O 2 R 1 E 0 Z Where first element is TOP of the stackThe execution will be as below: 1) The program function isPal will check if s has length 0 or 1: ZEROREZ does not have length 0 or 1, then the condition failed. 2) Now check character at 0 is same as character at length-1 index 3) True, then call isPla with new string that starts from index 1 to length-1 based on current string i.e. remove index 6 and 0 which forms new string as below: Index Stack Content 4 E 3 R 2 O 1 R 0 E 4) Now check character at 0 is same as character at length-1 index (length is 5 and index to be checked is 4) 5) True, then call isPla with new string that starts from index 1 to length-1 based on current string i.e. remove index 4 character and 0 which forms new string as below: Index Stack Content 2 R 1 O 0 R 4) Now check character at 0 is same as character at length-1 index (length is 3 and index to be checked is 2) 5) True, then call isPla with new string that starts from index 1 to length-1 based on current string i.e. remove index 2 character and 0 which forms new string as below: Index Stack Content 0 O 6) Based on point 1, the string length is 1, that returns a true value. Based on the execution mentioned in previous step, the function isPal will return a true value.