You create Microsoft Windows-based applications. You create a customer-support application for a technical support organization. The customer-support application accepts phone numbers. While running a report, you find that the phone numbers displayed do not follow a single format. In addition, there are instances of missing digits and missing area codes. You need to ensure that the phone numbers are entered in the format (###) ###-####. You want to achieve this goal by using the minimal amount of code. What should you do?

A.
Write code that uses a regular expression in the Validating event of the control.

B.
Write code that uses a regular expression in the TextChanged event of the control.

C.
Write a custom text box control to validate the input of the user.

D.
Replace all current TextBox controls that are used for phone number input with MaskedTextBox controls.