Which of the following is the MOST secure password?

A is less secure as it only uses uppercase, lowercase, and hyphens, lacking numbers and special symbols.

B is less secure as it only uses uppercase letters and hyphens, lacking numbers and special symbols.

C is less secure as it only uses lowercase letters, numbers, and hyphens, lacking uppercase letters and special symbols.

D is the most secure because it combines uppercase letters, lowercase letters, numbers, and special characters, which significantly increases its entropy and makes it much harder for brute-force or dictionary attacks to guess. The inclusion of substitutions like '@' for 'a' and '3' for 'e' also adds complexity beyond simple word variations.