Answer:
A. acceptance tests
Step-by-step explanation:
In acceptance testing, the system is tested for acceptability to the end user. In order to do this it needs to be validated against the specified requirements. The testing team derives the acceptance tests from the requirement specification.
It generally corresponds to the last phase of testing operations for the system when the system is considered stable enough to be offered to the end user. If the system fails to satisfy the acceptance testing criteria, it needs to go through further rounds of iterative development.