Which line$($s$)$ if any might crash when calling these functions in a multi$-$threaded program?if $($iter$)\{$ if $($iter$->$curr$)\{\}\}$

$\}$

void$*$ iter$\_$get$($iter$\_$t$*$ iter$)\{$ lock$($&mutex$)$; unlock$($&mutex$)$; $\}\}\}$Lines $4$&$13$

Line $4$

Line $5$

Line $15$

Lines $5$ & $15$

Lines $13$ & $15$

No crashes