Consider the following method, which is intended to count the number of times the letter $"$A$"$ appears in the string str$.$

public static int countA$($String str$)$

$\{$

int count $=0$;

while $($str$.$length$()>0)$

$\{$

int pos $=$ str$.$indexOf$("$A$")$;

if $($pos $>=0)$

$\{$

count$++$;

$/*$ missing code $*/$

$\}$

else

$\{$

return count;

$\}$

$\}$

return count;

$\}$

Which of the following should be used to replace $/*$ missing code $*/$ so that method countA will work as intended?