What is the optimal way to implement this?

A developer Is tasked with ensuring that email addresses entered into the system for Contacts and for a Custom Object called Survey_Response__c do not belong to a list of blacklisted domains. The list of blacklisted domains will be stored In a custom object for ease of maintenance by users. Note that the Survey_Response__c object is populated via a custom visualforce page.

What is the optimal way to implement this?
A . Implement the logic in an Apex trigger on Contact and also implement the logic within the Custom visualforce page controller.
B. Implement the logic in the Custom Visualforce page controller and call that method from an Apex trigger on Contact.
C. Implement the logic in a helper class that is called by an Apex trigger on Contact and from the Custom Visualforce page controller.
D. Implement the logic in a Validation Rule on the Contact and a validation Rule on the Survey_Response__c object.

View Answer

Answer: C