A . True, a single table column can be included in both a unique index and a non-unique index, provided they are different indexes.
D . True, an invisible index is maintained during DML operations, which means it is updated when insert, update, or delete operations are performed on the table. However, it is not used by the optimizer by default for query execution unless explicitly hinted or the session is altered to consider invisible indexes.
E . True, an index can be specified in the CREATE TABLE statement using the INDEX clause to create an index on a specific column at the time of table creation.
B, C, and F are not correct: B. A descending index is simply an index that is sorted in descending order, not a type of function-based index. C. A DROP INDEX