Why do scammers use a test question and answer?

When you receive a 419 email, you’ll often see that the scammer has included a test question and answer into the payment details.  Here’s why.  Let’s say for example that you’re abroad and lose/have your wallet stolen.  Not only have you lost your money, but any forms of ID too.  A quick call to a friend/relative abroad has them agree to send you money via money transfer service.  The problem is that you have no ID to collect money sent to you, so what do you do?  Agree on a question and answer that only you know is what you do.  Now you can go to the money transfer service, give them the transfer number and the test question/answer and collect the money.  Scammers use fake names, so abuse this legitimate service as a way to get the money from their victim without having to show any ID and give away any of their real details.  So now you know.