Cloud Kicks wants users to only be able to choose Opportunity stage closed won If the Lead source has been selected. How should the administrator accomplish this goal?

Making Lead Source a dependent picklist to Opportunity Stage would mean the available Lead Source values change based on the selected Stage, which is the opposite of the requirement and wouldn't enforce Lead Source if Stage is 'Closed Won'.

Changing the Opportunity Stage field to read-only would prevent users from selecting any stage, including 'Closed Won', which does not meet the requirement of allowing 'Closed Won' only under a specific condition.

A validation rule is the correct solution because it can enforce specific data entry requirements based on conditions across multiple fields. By configuring a validation rule that triggers an error when Opportunity.StageName is 'Closed Won' AND Opportunity.LeadSource is blank, it prevents users from saving records that violate this business logic.

Modifying Opportunity Stage as a dependent picklist to Lead Source would mean the available Stage values change based on Lead Source, which again is the opposite of the requirement.