Which of the following best describes acceptance testing?

Acceptance testing is primarily focused on verifying that the software meets the specified user requirements before it is delivered to the customer or deployed to production. This phase of testing is crucial because it assesses whether the end product aligns with the expectations and needs of the stakeholders, particularly from the perspective of the end-users.

This type of testing typically occurs after other types of testing, such as unit testing and integration testing, have been completed and ensures that the system as a whole functions according to the agreed functionalities. It is often conducted in a real-world environment where the software will be used, allowing for a practical evaluation of whether it meets the user's specifications.

The other options refer to different types of testing that are important but do not define acceptance testing accurately. For example, testing code at the unit level relates to verifying individual components for correctness, assessing system performance focuses on how well the system operates under certain conditions, and ensuring integration of various components pertains to checking how well different parts of the system work together. None of these capture the essence of verification against user requirements as the accepted definition of acceptance testing does.