You didn't give the options for us to choose from. But I do think I know what you are talking about. It is "Clipboard".
Answer And explanation
a)
has 1/
probability guess the correct source
b)
Each element in
is mapped by
/
. There are
So there are
-1 elements.
number of target elements = 
number of source elements =
-1
probability =
-1 /
c) Probability of the correct target element
1/
Yes, they can involve animals! Hope this helps(: