Ben's job is to ensure that data is labeled with the appropriate sensitivity label. Since Ben works for the US government, he has to apply the labels Unclassified, Confidential, Secret, and Top Secret to systems and media. If Ben is asked to label a system that handles Secret, Confidential, and Unclassified information, how should he label it?

a. Mixed classification
b. Confidential
c. Top Secret
d. Secret