A security manager meeting the requirements for the international flow of personal data will need to ensure:

A.
a data processing agreement.

B.
a data protection registration.

C.
the agreement of the data subjects.

D.
subject access procedures.

Explanation:
Whenever personal data are transferred across national boundaries; the awareness and agreement of the data subjects are required. Choices A, B and D are supplementary data protection requirements that are not key for international data transfer.