Assume you need to implement a function named getDescription$()$ in ItemList that accepts a bar code and returns the description of the item that matches the bar code. Which of the following is the correct implementation of a function getDescription$()?$

a$.$

QString ItemList::getDescription$($QString b$)$ const$\{$

return list.value$($b$)->$description;

$\}$

b$.$

QString ItemList::getDescription$($QString b$)$ const$\{$

return list.key$($b$)->$description;

$\}$

c$.$

QString ItemList::getDescription$($QString b$)$ const$\{$

return list.value$($b$)->$getDescription$()$;

$\}$

d$.$

QString ItemList::getDescription$($QString b$)$ const$\{$

return list.key$($b$)->$getDescription$()$;

$\}$