What is a Quality Assurance (QA)?
Quality assurance is process-focused and preventive: it asks "are we working in a way that will produce good deliverables?" — audits, process checklists, standards, peer-review practices. It happens while work is being done, on the process itself.
The exam contrast: QA manages the process (prevention); quality control inspects the product (detection). If the scenario involves auditing whether the team follows the coding standard, that's QA. If it involves testing the finished build, that's QC.
Worked example
On a hospital construction job, QA is the monthly audit confirming welders hold current certifications and every weld procedure follows spec — before and during the work. Nobody is X-raying a finished weld yet; they're making sure the process can't easily produce a bad one.