If I run a company, I’ll hire you to do work that pays off more than what I pay you to do it. Today, virtually no employer knows whether hiring a person will pay off. That’s why you need to know how to walk into a manager’s office and demonstrate, hands down,how you will ...
B, and C all have perfect security1, if you use the same password at all of them and for service “D”, which has poor security, your single password for everything stands a very good chance of being discovered.