A password string, pwd, consists of binary characters (0s and 1s). A cyber security expert is trying to determine the minimum number of changes required to make the password secure. To do so, it must be divided into substrings of non-overlapping, even-length substrings. Each substring can only contain 1s or 0s, not a mix. This helps to ensure that the password is strong and less vulnerable to hacking attacks.
a) 0
b) 1
c) 2
d) 3