Final answer:
A registry must enter into a data use agreement when sharing de-identified data only if there is access to files with known disclosure risk.
Step-by-step explanation:
A registry m+ust enter into a data use agreement when sharing de-identified data only if there is access to files with known disclosure risk. This is because de-identified data, while stripped of direct identifiers such as names and social security numbers, may still contain indirect identifiers or other elements that could potentially be used to re-identify individuals. Therefore, a data use agreement is necessary to ensure that proper safeguards are in place to protect the privacy of the individuals whose data is being shared.