Which of the following is the MOST important consideration when processing personal data for an...

Before any processing, CDPSE stresses lawfulness: identify and document the appropriate legal basis and processing purpose(s). Security controls (C), algorithmic techniques (B), and aggregation (D) are important but secondary to establishing a lawful basis and purpose limitation.

Key CDPSE-aligned phrasing (short extract): “Processing requires a lawful basis and defined purposes prior to collection/use.”