The kind of index which is based on any candidate key or a non key field which may have duplicate values is classified asa)ternary indexb)clustering indexc)primary indexd)secondary inde

The kind of index which is based on any candidate key or a non key field which may have duplicate values is classified as a secondary index (d).

Here's why:

a) A ternary index is not a standard term in database indexing.

b) A clustering index is an index that reorders the way records in the table are physically stored. Therefore, it cannot have duplicate values.

c) A primary index is an ordered file whose records are of fixed length with two fields. The first field is the same a primary key, and second field is a set of pointer field. So, it also cannot have duplicate values.

d) A secondary index may be generated from a field which is a candidate key and has a unique value in every record, or a non-key with duplicate values. So, the correct answer is d) secondary index.