DOCUMENT();

loadMacros(
	'PGstandard.pl',
	'MathObjects.pl',
	'PGML.pl',
	'parserGraphTool.pl',
	'PGcourse.pl'
);

$graph0 = GraphTool('{parabola,solid,vertical,(0,0),(1,1)}')->with(cmpOptions => { checker => sub { return 1; } });
$graph1 = GraphTool();
$graph2 = GraphTool('{parabola,solid,vertical,(1,0),(2,1)}')->with(cmpOptions => { checker => sub { return 1; } });

BEGIN_PGML
If possible, draw parabolas (using a solid line) which satisfy each of the following conditions individually. If it is
impossible to satisfy a condition, just leave the graph empty.

a. A parabola which is an even function
[@ LABELED_ANS($graph0->ANS_NAME, $graph0->cmp); $graph0->ans_rule @]*

a. A parabola which is an odd function
[@ LABELED_ANS($graph1->ANS_NAME, $graph1->cmp->withPreFilter('erase')->withPostFilter(sub {
	my $ans = shift;
	$ans->{score} = 1 if $ans->{student_value} eq '';
	return $ans;
})); $graph1->ans_rule
@]*

a. A parabola which is neither even nor odd
[@ LABELED_ANS($graph2->ANS_NAME, $graph2->cmp); $graph2->ans_rule @]*
END_PGML

ENDDOCUMENT();