Oak wholly owns a material subsidiary, Birch. Birch has a material 30% interest in Willow. Oak also owns 40% of Beech, which is material to Oak. Birch is an IESBA Public Interest Entity audit client. Which of the following would be restricted entities? Oak, Birch, and Willow Birch and Willow Oak, Birch, Willow and Beech Birch, Willow and Beech 4