You create Microsoft Windows-based applications. You are designing a reusable composite control for a customer service application. The composite control contains three TextBox controls. The first TextBox control is used for the customers account number. The second TextBox control is used for the customers phone number. The third TextBox control is used to hold the last four digits of the customers social security number. The composite control is used to retrieve a customers insurance data. You need to ensure that data is entered in the valid format for all the three TextBox controls. Which action should you perform to achieve this goal?

A.
Override the TextChanged event of the composite control to validate all the TextBox controls.

B.
Write custom code in the TextChanged event of the third TextBox control.

C.
Override the Validating event of the composite control to validate all the TextBox controls.

D.
Write custom code in the Validating event of the third TextBox control.