Let A = {x1 , x2 ,......, x7 } and B = {y1 , y2 , y3 } be two sets containing seven and three distinct elements respectively. Then the total number of functions f : A → B that are onto, if there exist exactly three elements x in A such that f(x) = 1/2 , is equal to :
(1) 14.7C3
(2) 16.7C3
(3) 14.7C2
(4) 12.7C2