DOCUMENT();

loadMacros('PGstandard.pl', 'PGML.pl', 'parserCheckboxList.pl', 'PGcourse.pl');

# have 1 or 2 incorrect answers
$numberOfIncorrect = random(1,2);

# randomly choose which are incorrect
@whichAreIncorrect = random_subset($numberOfIncorrect, (0,1,2));

# make the array of which are CORRECT, which is so much more complicated in Perl than it is in Python
@whichAreCorrect = (0,1,2);
for $remove (@whichAreIncorrect) {
    @whichAreCorrect = grep { $_ != $remove } @whichAreCorrect;
    }

# the correct answers
@answers = (3,5,8);

# make these answers incorrect by adding one to them
for (@whichAreIncorrect) { $answers[$_] += 1; }

$checks1 = CheckboxList(
    [
        "\(1+2=$answers[0]\)",
        "\(2+3=$answers[1]\)",
        "\(4+4=$answers[2]\)",
        'None of the above'
    ],
    @whichAreCorrect
);

BEGIN_PGML
Choose which equations are correct:
[_]{$checks1}
END_PGML
ENDDOCUMENT();