Question

WILL MEDAL AND FAN BEST ANSWER!!!
Is the key for this correct?

Answer 1

What you're asking is quite ambiguous / unclear. If you're given a "key," and it's really a "key," then you can assume it's correct. What, specifically, do you need to know? What have you done so far towards addressing this problem?

Answer 2

@mathmale I made the key, so I just wanted to make sure that when I said there was a universal set, there was, etc.