Which of the following would MOST likely trigger the extraterritorial effect of the GDPR, as...

According to Article 3(1) of the GDPR1, personal data shall be processed in any member state only on the basis of a decision taken at a Union level that is binding for that member state, unless it is derogated from by national law. This means that the GDPR applies to any processing of personal data within the EU, regardless of where the controller or processor is located, as long as it is based on a decision made at a Union level that is binding for that member state.

Therefore, option B would most likely trigger the extraterritorial effect of the GDPR, as it involves personal data of EU citizens being processed by a controller or processor based outside the EU, which may be subject to a decision made at a Union level that is binding for that member state.

Option A would not trigger the extraterritorial effect of the GDPR, as it involves monitoring suspected terrorists, which is not considered processing under Article 4(1) and (2) of the GDPR1. Monitoring may fall under other legal frameworks, such as national security or counter-terrorism laws.

Option C would not trigger the extraterritorial effect of the GDPR, as it involves monitoring EU citizens outside the EU by non-EU law enforcement bodies, which may not be subject to any decision made at a Union level that is binding for that member state.

Option D would not trigger the extraterritorial effect of the GDPR, as it involves processing personal data of EU residents by a non-EU business that targets EU customers, which may not be subject to any decision made at a Union level that is binding for that member state.

References: 1: Free CIPP/E Study Guide - International Association of Privacy Professionals.