Quality is delighting customers
I have an article about "10 Things To Consider When Evaluating Quality Assurance Testing Companies For Outsourcing" and here is the link https://qualityassurancetestingxperts.blogspot.com/2018/12/10-thing...
As per practices of quality assurance services, Quality Assurance(QA) is a verification process which ensures that desired quality level of product is achieved while each phase of its designing before releasing it to the market.
Quality Control(QC) is not a process but a validation technique by following which bugs/defects/faults are found in the product as per the set standards.
Testing is a process of executing complete product features to detect bugs so that they can be fixed before delivering it to the end users. Testing can be considered as a subset of Quality Control as it ensures whether product runs the way it is expected and designed for.
For conclusion, Quality Assurance can be said as preventive action, however, Quality Control can be said corrective measure and testing is considered as subset or part of QC.