Cersion 2.0 Choice activity. File choice/lib.php, near line 444.
$choice_option = $DB->get_record("choice_options", array("id" => $optionid));
fails in its attempt to get limit information for a choice option.
In my copy, I have substituted the expression: "$choice->maxanswers[$optionid];" to get the limit number, but the code seems to go out of its way to avoid that for some reason.