* A. Unify all three triggers in a single trigger on the Expense__c object that includes all events:
* Salesforce best practices recommend having only one trigger per object to avoid redundancy and conflicts.
* By combining all the events (before delete, before insert, and before update) into a single trigger, the developer can manage the logic in an organized and maintainable manner.
* This also simplifies debugging and ensures that the trigger logic executes in a predictable order.
* C. Create helper classes to execute the appropriate logic when a record is saved:
* Using helper classes allows for a clean separation of concerns. The trigger becomes a dispatcher that delegates logic to dedicated classes.
* For example, you can create methods like applyDefaultsToExpense(), validateExpenseUpdate(), and deleteExpense() in a helper class and invoke them from the trigger.
* This improves reusability, readability, and testability of the code.
Why not the other options?
* B. Unify the before insert and before update triggers and use Flow for the delete action:
* While Flow is a powerful tool, it is not ideal for deleting records or replacing Apex trigger functionality, especially when triggers already exist for other events.
* D. Maintain all three triggers on the Expense__c object but move the Apex logic out of the trigger definition:
* Maintaining multiple triggers on the same object can lead to conflicts and execution order issues, even if the logic is moved to helper classes.
References:
Trigger Best Practices
Trigger Design Patterns

* LimitException cannot be caught in a try-catch block because it is thrown when governor limits are exceeded, and Salesforce does not allow further processing in such cases.
* Other exceptions, such as custom exceptions, NoAccessException, or CalloutException, can be caught and handled.