The correct answer is A. Failure to demonstrate that consent was given by the data subject to the processing of their personal data where it is used as the basis for processing is an infringement that may result in an administrative fine of up to 10 million euros (or in the case of an undertaking, up to 2% of the total worldwide annual turnover of the preceding financial year) under the GDPR (Article 83(4)).
Failure to implement technical and organizational measures to ensure data protection is enshrined by design and default, failure to process personal information in a manner compatible with its original purpose, and failure to provide the means for a data subject to rectify inaccuracies in personal data are all considered more serious infringements and may result in much higher fines (up to 20 million euros or up to 4% of the total worldwide annual turnover of the preceding financial year, whichever is higher).