Comprehensive and Detailed Explanation From Exact Extract:
A (Correct):AnApproval Processcan lock a record (making it read-only) once the record meets certain criteria like stage = Closed/Won.
B (Correct):AValidation Rulecan prevent users from saving changes when the stage is Closed/Won, by throwing an error.
Example validation formula:
text
CopyEdit
AND(ISCHANGED(StageName), ISPICKVAL(StageName, "Closed Won"))
Incorrect options:
C:Before triggers run before the record is saved but don't prevent UI-level edits unless combined with DML rollbacks or errors.
D:Auto-response rules are for sending emails, not restricting edits.
Reference:Salesforce Help - Locking Records with Approval ProcessesValidation Rules Guide This topic relates to bothProcess Automation and Logic (30%)andSecurity and Data Integritypractices.