Fill in the code to complete the following method for checking whether a string is a palindrome.

```
public static boolean isPalindrome(String s) {
return isPalindrome(s, 0, s.length() - 1);
}

public static boolean isPalindrome(String s, int low, int high) {
if (high <= low) // Base case
return true;
else if (s.charAt(low) != s.charAt(high)) // Base case
return false;
else
return _______________________________;
}
```
a. isPalindrome(s)
b. isPalindrome(s, low, high)
c. isPalindrome(s, low + 1, high)
d. isPalindrome(s, low, high - 1)
e. isPalindrome(s, low + 1, high - 1)

e. isPalindrome(s, low + 1, high - 1)