Quiz Question

Here is a quiz question. What is the difference in meaning between these two statements.

1. Someone we both don't know
2. Someone we don't both know

a. In #1 you and I know the person, in #2 neither you nor I know the person.
b. In #1 only one of us knows the person, in #2 you and I know the person.
c. In #1 neither you nor I know the person, in #2 only one of us knows the person.
d. In #1 only one of us knows the person, in #2 neither you nor I know the person.

This can be tricky! I'll post an answer in the next blog entry.