The sales management team at Universal Container requires that the Lead Source field of the Lead record be populated when a.. converted. What should be done to ensure that a user populates the Lead…

A formula field displays a calculated value but cannot prevent a record from being saved or an action from being performed based on its value being empty.

A validation rule is the appropriate declarative tool to enforce data quality and prevent users from saving records or performing specific actions, such as converting a Lead, if the 'Lead Source' field is blank, prompting them to populate it.

Lead Conversion field mapping defines how fields from a Lead record map to fields on other objects during conversion; it does not enforce data entry on the Lead itself prior to conversion.

An after trigger on Lead could be used, but it's a programmatic solution (Apex) which introduces higher maintenance overhead compared to a declarative validation rule for this straightforward data entry requirement.