What is wrong with the following program?

int add$($int a$,$ int b$)$;

int main$()\{$

int x $=1$;

int y $=5$;

return add$($x$,$ y$)$;

$\}$

Group of answer choices

add$()$ has no definition

add$()$is called with x and y$,$ but accepts a and b

the program does not compile because main$()$ cannot return a value of $6$

a function cannot be called after a return statement

nothing is wrong with this program