Let $A=\{x_1,x_2....,x_7\}$ and $B= \{y_1,y_2,y_3\}$ be two sets contains seven and three distinct elements respectively. Then the total number of function $f:A \to B$ that are onto , if there exist exactly three elements x in A Such that $f(x)=y_2$ , is equal to :

Question

$\begin{array}{1 1} 14.^7C_2 \\ 16.^7 C_3 \\ 12.^7C_2 \\ 14.^7C_3 \end{array}$