Which area of user acceptance testing (UAT) was overlooked?

Cloud Kicks is creating a new lead conversion process in Sales Cloud. During a recent sprint, the business analyst created user stories related to the Opportunity object. Test scripts were created for the lead conversion process. All of the test scripts passed and the new functionality was deployed. After deployment, end users reported error messages when manually creating new Opportunities.

Which area of user acceptance testing (UAT) was overlooked?
A . Functionality on interconnected objects should be part of UAT.
B. Several teams should be part of UAT to represent multiple viewpoints.
C. End users who are experts in that functionality should participate in UAT.

Answer: C