Which two testing techniques should you use?

You are identifying the approach and techniques to use when testing a system. Each build of
the system will require retesting over 5000 test cases.
A new build of the system is performed every two days.
You must fully retest all 5000 test cases before the next build is complete.
Which two testing techniques should you use? (Choose two.)

A.
Stress testing

B.
Manual testing

C.
Regression testing

D.
Automated testing