Explanation:

**Data inconsistency** is a direct reason for problems of data integrity. Data integrity ensures data is accurate, complete, and consistent. Inconsistency occurs when the same data exists in different forms or locations and these versions do not match, leading to unreliable information. * **Option A (Data redundancy):** Data redundancy (storing data multiple times) can *lead* to inconsistency if not managed, but inconsistency itself is the direct integrity problem. * **Option B (Data inconsistency):** This is the correct answer. Inconsistent data directly violates data integrity, as the data is no longer reliable or accurate. * **Option C (Security constraints):** Security constraints are measures to *protect* data integrity and prevent unauthorized access or modification, not a cause of integrity problems. * **Option D (Unauthorized access of data):** Unauthorized access is a security breach that *can result* in data integrity problems (e.g., data corruption), but the integrity problem itself is the state of the data (e.g., inconsistency), not the act of access.