The techniques used to handle the phantom problem are

A. Time stamping
B. Index locking
C. Predicate locking
D. Execution indexing

The phantom problem occurs in database concurrency control when a transaction re-executes a query and finds new rows inserted by another transaction.

Techniques used to prevent phantom problem:

• Index locking – locks index ranges to prevent insertion of new tuples in the range.
• Predicate locking – locks records satisfying a condition.

Time stamping and execution indexing are not specifically used to solve phantom problem.

Therefore, correct options are B and C.