291In particular, in Case C-90/09 PGeneral Química and Others v Commission [2011] ECR I-1, paragraphs 104 to 109, and Case C-521/09 PElf Aquitaine v Commission [2011] ECR I-8947, paragraphs 153, 167 and 168, the Court of Justice emphasised the importance of examining the arguments put forward by the undertakings on which penalties have been imposed concerning the rebuttal of the presumption that the parent company does in fact exercise decisive influence over its subsidiary.