jnu 2010 probability

Posted by kratika on May 15, 2012; 6:39am
URL: http://discussion-forum.276.s1.nabble.com/jnu-2010-probability-tp7559331.html

a function is selected at random from all the functions of the set A={1,2,3......,n} into itself. the probability that the function selected is one-to-one is

a. 1/n^n
b. 2/(n-1)!
c. 1/n!
d. (n-1)!/n^n-1


is the answer option d??? plz confirm.....thanks!