Correct Answer - Option 3 : the data records of the file are organized in the same order as the data entries of the index.
Answer: Option 3
Concept:
Primary index:
It is defined on an ordered data file and the data file is ordered on a key field. The key field is generally the primary key of the relation.
Clustering Index:
It is defined on an ordered data file. The data file is ordered on a non-key field.
Secondary index:
It may be generated from a field that is a candidate key and has a unique value in every record, or a non-key with duplicate values only dense ordering in the non-clustered index (Secondary index) as sparse ordering is not possible because data is not physically organized accordingly
Multi-level Index:
Index records comprise search-key values and data pointers. The multi-level index is stored on the disk along with the actual database files.
B/B+ tree index → Multi-level index
Explanation:
The only option matches with the definition of the Clustered index in Option 3.
because for Clustered index two necessary things 1. index on non-key fields 2. must be on ordered data file.
Option 1 and Option 2 will be a clustered indexes.
Option 4 violates the ordered data file property, of the clustered index.
Hence Option 3 is correct.