Which GDPR Requirement Will Present the Most Significant Challenges for Organizations

Which GDPR requirement will present the most significant challenges for organizations with Bring Your Own Device (BYOD) programs?

A) Data subjects must be sufficiently informed of the purposes for which their personal data is processed.
B) Processing of special categories of personal data on a large scale requires appointing a DPO.
C) Personal data of data subjects must always be accurate and kept up to date.
D) Data controllers must be in control of the data they hold at all times.