* Option A (Apex Class): Trace flags can be configured for specific Apex classes to debug issues during their execution.
* Option C (User): Trace flags can be set for specific users to debug issues occurring in their transactions.
* Option E (Apex Trigger): Trace flags can be set for specific triggers to debug execution.
Not Suitable:
* Option B (Flow): Trace flags cannot be configured for Flows directly.
* Option D (Visualforce): Trace flags are not used to debug Visualforce pages directly.