Consider the following $3$ programs:

$123$

$//$contents of file foo.c: int a $=5$; int main$()\{$ f$()$; return $0$; $\}//$contents of file bar.c: extern int a; void f$()\{$ printf$("\%$d

$",$ a$)$; $\}$

$//$contents of file foo.c: int a $=5$; int main$()\{$ f$()$; return $0$; $\}//$contents of file bar.c: static int a $=4$; void f$()\{$ printf$("\%$d

$",$ a$)$; $\}$

$//$contents of file foo.c: int a $=5$; int main$()\{$ f$()$; return $0$; $\}//$contents of file bar.c: int b; void f$()\{$ printf$("\%$d

$",$ b$)$; $\}$

If the command $"$gcc foo.c bar.c$"$ is executed, which of the above programs do not result in a linker error

Group of answer choices

$2$ and $3$

$3$ only

$2$ only

$1,2,$ and $3$

$1$ only