Final answer:
The best overall classification for a system handling various types of sensitive data would be 'high confidentiality' and 'high integrity' to cover the strictest controls needed across all data types, with less emphasis on 'availability' in this context.
Step-by-step explanation:
The overall classification of a system containing PII (Personal Identifiable Information), financial, and proprietary data based on the data classification table provided would need to encompass the highest levels of control from each data type for confidentiality, integrity, and availability. When considering each characteristic (confidentiality, integrity, and availability), the system would need to be classified at the highest level of control required for each characteristic across all types of data it handles.
In this case, the table indicates that confidentiality is generally high across PII, proprietary, and competitive data. Integrity requirements are high for proprietary and medium for the other types of data. Availability varies but is not the dominant factor for the highest control level required. Therefore, the best overall classification for this system would be high confidentiality and high integrity since the engineer must ensure the strictest controls for the most sensitive data.
The focus on confidentiality and integrity ensures that the sensitive data is both protected from unauthorized access and maintained with a high degree of accuracy and reliability. Availability, while important, falls behind in priority when it comes to high-value data types that are more sensitive to breaches and manipulation.