Question 21
UnclassifiedK-anonymity ensures that each record is indistinguishable from at least:
Correct answer: B
Explanation
K-anonymity requires that each record share the same quasi-identifier values with at least k records total, so it is indistinguishable from "k-1 other records" in that equivalence class. This means an attacker cannot single out one person from the quasi-identifiers alone.
Why each option is right or wrong
A. 1 other record
B. k-1 other records on quasi-identifiers
Under the formal definition of k-anonymity, every equivalence class formed by the quasi-identifiers must contain at least k records, so any one record is hidden among a total of k indistinguishable records. That means the target record cannot be separated from the other k-1 records in the same class based on quasi-identifier values alone, which is exactly the minimum anonymity set size required by the model.
C. All records in the dataset
D. K_min records by primary key