Exam PRINCE2-Practitioner topic 21 question 9 discussion

During the 'accept a work package' activity, the team manager for the marketed courses' asked project assurance for advice on reviewers. The team manager was unsure who from the sales team should be involved in reviewing the advertisements to ensure that they will deliver the required sales. The team manager then added the new reviewers and their responsibilities to the team plan.
Which theme is being applied by consulting project assurance?