Final answer:
A qualification of a difficult-to-decode password is a combination of uppercase and lowercase letters, numbers, and special characters.
Step-by-step explanation:
The qualification for a password that is difficult to decode is option C) A password that includes a combination of uppercase and lowercase letters, numbers, and special characters. This type of password is known as a strong password. A strong password is essential for ensuring the security of employee computers and protecting sensitive data from unauthorized access.