Fault base testing technique is

Fault based testing is a testing technique in which artificial faults are introduced into a program.

The purpose is to check whether the test cases are strong enough to detect those faults.

Mutation testing follows this idea.

In mutation testing, small changes are made in the program to create mutants.

If test cases detect these mutants, then the test cases are considered effective.

Now check the options:

Unit testing checks individual modules.

Beta testing is done by real users before final release.

Stress testing checks system behavior under heavy load.

Mutation testing is a fault based testing technique.