In which testing strategy are the requirements established during requirements analysis validated against the developed software?

Explanation

Validation testing begins when integration is complete and checks the assembled software against the requirements established during requirements analysis — it answers Boehm's question "Are we building the right product?" and succeeds when the software behaves as the customer's requirements specification demands. Integration testing only checks that the modules work correctly when combined, exercising interfaces rather than customer requirements. Regression testing re-runs earlier tests after a change to confirm nothing has broken. System testing exercises the complete, validated software together with the hardware, people and other system elements. Hence the answer is validation testing.